With the continuous improvement of computer automation, substation automation has become a development direction for power companies. It can improve the operational level of substations, reduce operation and maintenance costs, and offer high safety and reliability, truly achieving the goal of reducing manpower and increasing efficiency. Therefore, when constructing the 220 kV Xintang substation in 1998, Zengcheng Branch decided to adopt a comprehensive substation automation system. Based on the characteristics of the Xintang substation and its importance in the power grid, several requirements were put forward for its construction: a) High reliability. All important functions that could affect the normal and safe operation of the substation and power grid should be dual-function without common links to ensure uninterrupted full-function operation even in the event of hardware failure or software malfunction. b) Strong practicality. It should be suitable for both unmanned substation operation and on-site monitoring and operation by operators, while meeting the requirements of system automation and modern operation management. c) Advanced technology and flexibility. The system uses mature and advanced hardware and software technologies, has a reasonable and reliable network structure, is easy to operate and maintain, can adapt to future substation expansion, meets the requirements of an open system, and can connect to microcomputer protection and automation devices from any manufacturer. In response to the characteristics and requirements of Xintang Substation, Zengcheng Branch adopted the latest CSC2000 integrated automation system from Sifang Company. [b]1 Composition of the CSC2000 Integrated Automation System[/b] The CSC2000 integrated automation system adopts a hierarchical distributed structure, consisting of the following three parts: a) Distributed configuration of integrated equipment at the bay level. Primary equipment (one main transformer, one line, etc.) within the substation is configured horizontally and distributed at the bay level. The function of this layer is to digitize analog and digital quantities; to have independent protection, measurement, and local operation functions; and to serve as the interface between the system and the primary equipment. b) Substation communication network. Its function is to collect the uploaded information from each integrated device and then issue control commands. The communication network adopts the LonWorks bus-type network produced by Echelon Corporation of the United States, with a hierarchical distributed bus structure, and the three networks are independent of each other. To improve reliability, dual monitoring networks A and B are set up. Important bay level equipment, such as 220 kV bays, main transformer bays, and central signals, are simultaneously connected to networks A and B. 110 kV and 10 kV bay equipment are connected to network C. The waveform recording network primarily provides data from waveform recording modules distributed across various protection devices and data recorded by centralized dedicated waveform recording screens to engineers' workstations for storage. All devices on the communication network are connected using symmetrical twisted-pair cables in the same manner. Carrier Sense Multiple Access (CSMA) with collision detection (CD) is used for information transmission. A key feature of the LonWorks network is its improved CSMA, a new Predictivep-Persis-Tewt CSMA that automatically adjusts the random latency of each node according to network load. During network congestion, the random latency of nodes automatically increases to reduce collisions, and vice versa, increasing throughput. Furthermore, it can set priorities, minimizing latency for important information and sending it first, thus minimizing media access delays under light loads and minimizing the possibility of collisions under heavy loads. Each node in the LonWorks network uses high-voltage pulse transformer isolation, so the common bus section is simply a passive cable, resulting in extremely high reliability. Each connection point to the network is equipped with a small electromagnetic relay and a corresponding detection circuit. This relay automatically disconnects the node from the network when an abnormality is detected, ensuring normal communication for the remaining nodes. Adding or removing nodes on the network is very convenient; the removal of any node does not affect the communication of other nodes. New nodes can be placed anywhere, simply by connecting to the bus. Moving existing nodes does not require any changes to the network initialization file. The LonWorks network communication speed is 78 Kbit/s, the maximum communication distance is 2 km, and the maximum throughput is 400 frames/s. Each frame can contain 0 to 288 bytes of valid data; therefore, the design should avoid excessively long frame structures to prevent collisions. When transmitting large blocks of data, they can be divided into several short packets, ensuring that other information with priority can preempt the medium during the intervals between packet transmissions. c) Monitoring and communication system at the substation level. Its function is to connect downwards to the station's internal communication network, enabling all station information to smoothly enter the database, and to send it upwards to the dispatch and control center as needed, realizing remote communication functions; it also enables local monitoring functions through a human-machine interface and powerful data processing capabilities, serving as the interface between the system and operators. The equipment at the substation level includes 2 local monitoring master stations, 4 remote control master stations, 1 engineer workstation, and 1 reactive power workstation. The substation level also adopts a distributed structure, with local monitoring and remote control master stations being identical yet independent of each other. A switching circuit is provided, allowing selection of connection to network A or network B, and communication with the local monitoring PC via a serial port or other communication interface, or connection to the remote control center via a modem channel. Damage to one component at the substation level does not affect the normal operation of other components, as they share information on the network. [b]2 Local Monitoring Master Station[/b] Local monitoring master stations 1 and 2 have identical hardware and software, both connected to the LonWorks network simultaneously. One operates as the master station, performing communication with the network, while the other is in hot standby mode. When the primary station fails, the backup station automatically switches to primary mode and takes over communication. Once the primary station recovers, the backup station retransmits the lost historical data to the primary station, ensuring the primary station's historical database remains intact. This dual-machine hot backup method guarantees no loss of real-time or historical data, increasing redundancy and improving reliability. The SCADA monitoring software on the monitoring machine runs on a 32-bit Windows NT4.0 operating system. This system has true preemptive multitasking and multithreading capabilities, providing an environment ideally suited for SCADA applications. When the monitoring machine needs to execute several tasks simultaneously, each task runs in its own environment with its own priority, and the operating system allocates CPU execution. Preemptive multitasking and multithreading technology effectively schedules all loaded tasks and allocates CPU time to the most critical tasks. Its core service program consists of several concurrently running threads, such as communication sampling, alarm generation, historical recorder, printing, and network threads. Each thread executes its own task and can run simultaneously, resulting in high reliability, high performance, and data integrity. The SCADA monitoring system possesses extremely powerful handling capabilities in accident situations. This system is built on a fast, network-protocol-based, and event-driven information transmission foundation. Its communication bus can handle large amounts of data in a short time without bottlenecking. The software kernel allocates 10,000 information lines to each internal or external module. Information exchange between different modules is event-driven; only new or changed values ​​are exchanged. This balances CPU consumption, maintains high CPU performance, and allows the software to receive and process thousands of events and accurately record them in the historical database without data loss. The system can define up to 65,000 control points and handle 65,000 alarms simultaneously. The system can define alarm severity levels from 0 to 50,000 and can simultaneously invoke up to 20 different alarm windows. Each alarm displays a specific type of alarm. Particularly severe alarms directly trigger an alarm pop-up window on the screen to display alarm information, while simultaneously activating the electric bell or emergency sound. The open architecture of the SCADA system allows it to interconnect with other systems. Other systems and application software can exchange real-time and historical data using standard methods and common interfaces. Virtual File Interfaces (VFIs) serve as the interface layer between the system and data files. These layers allow the system to record and save data in common file formats. Application Programming Interfaces (APIs) allow users to access system data directly from user programs or application modules. Dynamic Data Exchange (DDE) is supported, enabling the exchange of real-time data between two independent applications. The system's SQL interface can execute user-defined SQL commands, with users embedding control points as parameters to compose records in a custom format for data transmission. The SQL interface also supports Microsoft's Open Database Connectivity (ODBC) interface, allowing the system to access various commonly used database system files. The SCADA system has features to prevent unauthorized operation. It can authorize over 500 users while ensuring security. Users are grouped based on their nature, region, or organizational structure. Each control object in the system, such as control points, graphical layers, menu items, and macros, is assigned to a specific user group; only users within that group can operate these objects. Users can enter a unique user identifier and password to access the system. Once logged in, the system will hide objects outside the user's authorized scope or prohibit operation on these objects based on the user's authorized group. The system can also be integrated with microcomputer-based five-prevention devices to provide anti-misoperation functionality during local operation. The SCADA system also features a rich and user-friendly human-machine interface, a powerful graphical interface, a vast component library, and over 100 communication drivers. It can automatically generate various reports, record historical alarms and protection events, and can be viewed, displayed, and printed at any time. [b]3 Remote Control Station[/b] The remote control station adopts the Sifang CSM300C basic model. It is based on a hierarchical distributed fieldbus network structure of LonWorks, using a 32-bit industrial control PC as the host, running on the common DOS/Windows NT operating system. The remote control station is connected to the station's internal communication network, forming a node in the LonWorks network. Within the station, the remote control station node communicates with other nodes according to the "CSC2000 System Internal Communication Protocol"; externally, the remote control station communicates with the dispatching terminal according to the external communication protocol. The remote control station plays a crucial role, acting as an analog network-type RTU, and compared to traditional substation RTUs, it has the following significant advantages. a) Large and Flexible Processing Capacity: Traditional RTUs have clearly limited processing capacity, specifying a maximum of three remote quantities (remote measurement, remote signaling, and remote control). Because the collected data is transmitted to the RTU terminals via secondary cables, and the physical number of terminals and related internal circuitry is finite, the maximum processing capacity of the RTU is fixed. In the CSC2000 automation system, the equipment at the bay level has already completed data acquisition. The remote control master station can conveniently collect various required data using the Lon-Works network, without limitations such as the number of terminals. Its processing capacity is mainly limited by CPU processing speed and the maximum throughput of the Lon-Works network. Under these constraints, its processing capacity is very large, sufficient to meet the actual needs of a substation. b) High Processing Speed, Flexible Communication Methods, and High Reliability: The remote control master station connects to the Lon-Works network, directly sending the collected data to an independent database. After protocol conversion, the data is sent to the dispatch master station. A significant portion of the work is now handled by the front-end equipment at the bay level, thus reducing the burden on the remote control master station. This allows for faster data processing, larger capacity, and more time for comprehensive information processing, while also greatly improving system reliability. Furthermore, the CSM300C supports commonly used remote control communication protocols in China, such as U4F/N4F, CDT, DNP3.0, SC-1801, IEC60870-5-101, FERRANTI, and UCA. All communication protocols are built into the CSM300C software, allowing the dispatching terminal to select different protocols according to different needs, offering great flexibility. c) Debugging and maintenance are convenient during online operation. The operating status can be monitored via a display. Messages from each front-end device, telemetry, telesignaling, power and SOE data for each RTU protocol, and communication data between the RTU and the dispatching master station can all be directly displayed on the screen. Users can issue simple commands to the front-end devices via the keyboard and can also simulate network information, simulating receiving or sending network messages. When a portable computer is needed for debugging, the standard serial port COMI of the industrial PC can be used to simulate the protocol and parameters of any channel. When the portable computer is connected to the COMI serial port, the system automatically finds and prompts the user to input the channel number to be simulated. The COMI serial port will then communicate the configuration of the input channel with the master station. This function allows remote commissioning to be performed directly at the dispatching end, which is flexible and convenient. [b]4 Relay Protection Engineer Workstation[/b] The relay protection engineer workstation is a node in the Lon Works network, connected to the station's communication network and waveform recording network. It can quickly save the waveform recording plug-in data scattered in various protection devices, as well as the recorded data from the centralized waveform recording screen, to disk. The waveform of the waveform recording data is displayed on the industrial PC for analysis and calculation. It is connected to the public telephone network via a modem and transmitted remotely to the relay protection engineer's work computer, allowing them to view and call up the required data instantly. Authorized relay protection engineers can also perform relay protection-related work such as setting reading and setting modification. **5 Reactive Power and Voltage Regulation Workstation** The reactive power and voltage regulation workstation is specifically used for switching on and off 10 kV capacitors and controlling the on-load tap changer mechanism of the main transformer. It is connected to the Lon-Works network, directly collects relevant analog and status information from the network, performs analysis and calculation, and issues commands for voltage regulation and capacitor switching to the network according to the set values ​​and action logic. The voltage regulation command is executed by the CSI301A device in the main transformer protection panel, achieving the comprehensive regulation function of reactive power and voltage. **6 Conclusion** The automated operation of the substation not only greatly reduces the labor intensity of the operators, but also provides accurate real-time data and graphics for dispatching and operating personnel, helping them to accurately grasp the operating status of the equipment. The 220 kV Xintang Substation Integrated Automation System is simple to operate, requires little maintenance, and has high operational reliability. It has been operating safely for more than 1,100 days since its commissioning, achieving good results and is worth promoting. **References** **［1］Li Chaoqun. Design of Automation System for 220 kV Buyecheng Substation［J］. Electric Power Automation Equipment, 2001, 21(9): 32-34. [2] Yu Yonghong, Xu Jiankun. Application of automation system in Baogai 220 kV substation [J]. Electric Power Automation Equipment, 2001, 21(12): 63-65.