Implementing computer monitoring systems in small hydropower stations can improve their automation level and economic efficiency, as well as increase their operational reliability and stability. Through investigation and research of some small hydropower stations, this paper analyzes the current status of computer monitoring system implementation and common problems. my country has a large reserve of small hydropower resources, widely distributed, and has become an important part of water resources in many regions. Currently, more than one-third of the country's electricity resources are provided by small hydropower stations, with over 800 counties relying primarily on them for power supply. Developing small hydropower stations has become an important way to promote rural electrification in my country. However, small hydropower stations built before the 1990s suffer from outdated equipment and management methods, low technical levels, poor safety performance, high accident rates, poor power quality, and low economic efficiency. With the successful application of computer monitoring systems in large hydropower stations, a number of small hydropower stations, starting with Sinotruk in the 1990s, have also successively implemented computer monitoring and automation upgrades. Among the small hydropower stations that have implemented computer monitoring and automation upgrades, the vast majority have been successful, especially those newly upgraded or put into operation in recent years. However, some defects still exist to varying degrees in the computer monitoring and automation systems of some small power stations. A few small hydropower stations have more serious problems, affecting the normal operation of the stations. Studying and analyzing these problems, summarizing experiences, and learning lessons will be beneficial for the future implementation and automation transformation of computer monitoring systems in small hydropower stations. 1. Implementation Status of Computer Monitoring Systems in Small Hydropower Stations In the small hydropower stations investigated and tested, the station capacity is generally 800-9600KW, and the single unit capacity is 400-3200KW. The basic situation of the computer monitoring systems of these stations is as follows: 1.1 Types of Computer Monitoring Systems Currently, there are four basic forms of computer monitoring in small hydropower stations: 1. Mainly based on conventional control devices, abbreviated as (CASC); 2. A simple dual setting of computer monitoring and conventional control devices, abbreviated as CCSC; 3. A main method of computer monitoring and a supplementary method of conventional equipment, built as CBSC; 4. A fully computerized method. Most small hydropower stations that have implemented computer monitoring and automation transformation adopt the CBSC method (mainly computer monitoring and supplementary conventional equipment) or the fully computerized monitoring method. It should be said that the level of computer monitoring systems was relatively high, belonging to the level of the late 20th and early 21st centuries. For example, the Maluwan Hydropower Station in Henan Province, with an installed capacity of 2500 kW and three generating units, underwent automation upgrades and implemented a computer monitoring system in 1996. It was one of the earliest power stations in Henan Province to implement computer monitoring. The station's automation system adopted a dual configuration of computer monitoring and conventional control. Both control systems can operate independently. This control method has a relatively complex structure, but its advantage is that the two systems can switch and provide backup, resulting in high reliability. After a period of operation, some problems arose with the station's computer monitoring system and automation components. In this case, the computer monitoring system could only monitor, not directly control, and the entire power station was controlled by the conventional system. The disruption to normal power generation was not affected by the computer monitoring system's intervention. With the improvement of computer technology and the reliability of automation components, most hydropower stations implementing computer monitoring systems can operate reliably. In particular, some newly built small power stations in the last two or three years have adopted a mode with computer monitoring systems as the main component and simple manual operation panels. This means that when the computer monitoring system malfunctions, a simple automated start-stop circuit consisting of manual operation buttons and conventional relays can be used to perform start-stop, load increase/decrease, and non-regulating operations, increasing system reliability. This configuration mode has been adopted by many small hydropower stations, increasing the reliability of hydropower operation on the one hand, and providing convenience for operators accustomed to conventional control systems on the other. 1.2 Functions of the Computer Monitoring System A survey was conducted on small hydropower stations that have implemented computer monitoring systems, and the design functions and currently implemented functions of their monitoring systems were analyzed. The computer monitoring systems of these power stations are designed for "unmanned operation" or "minimal human intervention." Their main functions include data acquisition and preprocessing, unit operating status detection and automatic recording and printing of operating parameters, normal automated operation of the units, mechanical and electrical protection of the units, automatic adjustment of active and reactive power, automatic generation control (AGC), automatic voltage control (AVC), and automatic operation of auxiliary equipment. The investigation revealed that the degree to which the control system design functions of different power plants were realized varied. Some power plants basically achieved the designed functions, while others could only achieve some of them. Commonly implemented functions include: normal automated operation of the generating units, such as normal start-up and shutdown; mechanical and electrical protection of the generating units, such as protection against overheating, low oil pressure, low bearing oil level, overspeeding, overcurrent, overvoltage, and overload; monitoring of the generating unit's operating status and automatic recording and printing of operating parameters; regulation of active and reactive power; and alarm and recording of accidents. Functions not commonly implemented include: Automatic Generation Control (AGC), Automatic Voltage Control (AVC), and communication with higher-level dispatching departments. Currently, no small hydropower station has been able to achieve "unmanned operation." 1.3 Structure of Computer Monitoring Systems The structure of computer monitoring systems can be categorized into centralized monitoring systems, functionally distributed monitoring systems, and hierarchical distributed monitoring systems. Currently, small power plants with a total capacity of 2000 kW and a limited number of generating units and simple control functions mostly adopt centralized monitoring systems. Small hydropower plants with a total installed capacity of more than 2000 kW mostly adopt hierarchical distributed monitoring systems. The entire monitoring system is divided into two layers: the plant-level layer and the unit-level layer (local unit LCU), connected by a local area network (LAN). Due to the small capacity of the power plants, the plant-level configuration is relatively simple, generally consisting of one or two computers serving as operator workstations, implementing functions such as printing and alarms, and storing historical data. With the development of computer technology, the plant-level layer mainly adopts a centralized structure, where all power plant control functions are concentrated in one or two operator workstations. Considering the reliability and stability of unit operation, the local unit (LCU) mainly includes the unit LCU, common equipment LCU, and substation LCU. The structure of the local unit generally adopts the form of industrial control unit (IPC) + programmable logic controller (PLC) + automation device or programmable logic controller (PLC) + automation device. Commonly used automation devices include: microcomputer speed controllers, microcomputer synchronization devices, temperature monitoring devices, microcomputer excitation disconnection devices, and microcomputer-based speed measuring devices. These automation devices can operate independently or communicate with the local unit's industrial control computer to receive instructions and provide feedback. The PLC mainly handles the unit's sequential operation and data acquisition functions; the industrial control computer mainly handles data processing, direct operation, historical event recording, alarms, human-machine interaction, communication with the plant-level computer, and communication with automation equipment. The functional LCU mainly performs auxiliary equipment status detection and control operations. The substation LCU mainly operates individual equipment, circuit breaker switching, and protects electrical equipment. 2. Problems Encountered During Implementation An investigation into the current status of small hydropower stations that have implemented computer systems and automation upgrades revealed some common problems in the automation upgrades or computer monitoring implementation of small hydropower stations. 2.1 In the selection of small hydropower stations, the installed capacity ranged from 1000kW to 9600kW, and the single unit capacity ranged from 500kW to 3200kW, which did not fully consider the power station capacity and single unit capacity. The computer monitoring systems all adopted a hierarchical distributed structure, and the unit units mostly used an IPC+PLC+automation device model. The main reason was the influence of factors such as the limited product variety, insufficient data, and poor staff quality at the time. There was a one-sided pursuit of equipment reliability without reconsidering the specific requirements of the power station and units, as well as the functions of the monitoring system. This inevitably led to a waste of equipment resources and funds. 2.2 The selection of automation devices and components was incompatible with the system. The investigation found that some power stations selected speed governors, synchronizing devices, and excitation devices that lacked communication interfaces with the computer monitoring system or had conflicting interface protocols, causing these automation devices to be unable to connect to the computer monitoring system normally. Some power plants, during the automation upgrades and implementation of computerized monitoring, failed to thoroughly analyze their crude oil equipment and did not equip themselves with the necessary sensors and instruments required for automation. Furthermore, they failed to promptly equip traditional manually operated equipment with electric, pneumatic, and hydraulic automated operating mechanisms. This resulted in the inability to send necessary signals from lower-level equipment to the computer monitoring system, and the inability to automatically execute system commands. In particular, even with a common LCU (Low-Level Unit), automatic keying of auxiliary systems was not achieved. In some hydropower plants, the selection of automation equipment from several different manufacturers for the same monitoring system led to incompatible parameters, inconsistent communication protocols, and non-standard data formats, causing significant difficulties in communication and debugging. Some power plants, even with equipment installed for many years, still could not achieve network connectivity. Moreover, when equipment malfunctioned, repairs had to be handled by different manufacturers, resulting in unclear responsibilities and finger-pointing. Even minor problems or localized faults often remained unrepaired for months, severely impacting the normal operation of the power plant. All these issues made it difficult to achieve a unified level of control in the computerized monitoring system, thus hindering the achievement of the technical requirements for minimally staffed or unmanned operation. 3. Severe Shortage of Technical Skills Among Power Plant Operators The operation and maintenance of computer monitoring systems and automated equipment require technicians with certain professional knowledge and computer skills. However, surveys of small hydropower stations that have implemented computer monitoring systems revealed that many operators have poor educational backgrounds and computer skills, lack sufficient understanding of the technical requirements of computer monitoring systems and automated equipment, and have not received adequate professional training. This prevents operators from fully understanding the basic principles and operating methods of the installed hardware and software, leading to errors in their use. Furthermore, when simple malfunctions occur in certain equipment and software systems, secondary development is impossible, severely impacting the normal operation of the power plant. 4. Conclusion According to the "Design Regulations for Computer Monitoring Systems of Hydropower Plants" (DL/TS065-1996), "Code for Retrofitting Small Hydropower Stations" (SL193-97), and "Technical Specifications for Automation Design of Hydropower Plants" (DL-TS081-1997) issued by the Ministry of Electric Power Industry of the People's Republic of China since 1996 (as well as the national standard "Design Code for Small Hydropower Stations" (GB50071-2002)), all existing and newly built small hydropower stations in China will eventually implement computer monitoring systems. Therefore, summarizing the experiences and lessons learned from the implementation of computer monitoring and automation retrofits in power stations that have already implemented them, and ensuring careful design, meticulous calculation of the construction process, and careful investigation and selection of equipment and manufacturers, can help newly built or soon-to-be-retrofitted power stations avoid detours, save funds, and make the systems more scientific and reasonable in implementing computer monitoring and automation retrofits.