Several Problems in Substation Automation System

1 Preface
At present, the automation system of substations has been widely used in substations at all levels, with high degree of automation and stable operation status. In actual operation, it fully utilizes the characteristics of advanced technology and reliable operation. The widespread application of substation automation systems in county-level substations has played a positive and crucial role in upgrading the protection monitoring system, improving the automation level of substations, achieving scheduling automation and automatic meter reading, constructing unmanned substations, and reducing manpower and increasing efficiency.
2 Problems in actual operation
2.1 Backend monitoring machine
2.1.1 Whether to set up a background monitoring machine. Currently, there are two views on whether to set up a background monitoring machine for county-level substation automation systems: one is to set up a background monitoring machine, and the other is not to set up a background monitoring machine. The first viewpoint is that current substations are still manned by multiple or few people, and setting up backend monitoring machines is convenient for on-site monitoring and management, installation and debugging of monitoring and protection systems, testing and adjustment of protection settings, and querying of accident records; The second viewpoint is that substations will eventually become unmanned, so there is no need to set up backend monitoring machines. In fact, due to the condition of the equipment, the fact that most county bureaus have not yet established dispatch automation systems, and the inability to immediately achieve unmanned operation, new and renovated substations still have on duty personnel. Even if true unmanned operation can be achieved in the future, it will still take a long time. Therefore, based on practical needs, substations should be equipped with background monitoring machines. Therefore, when ordering substation automation systems, background monitoring machines and corresponding monitoring software should be ordered at the same time to prevent reordering and increasing investment if they cannot meet actual needs.
2.1.2 Management of backend monitoring machine operation
Practice has shown that the operation and management of backend monitoring machines are very important. In actual operation, there have been multiple instances where the backend monitoring machine has been paralyzed and unable to work due to human factors and the monitoring machine itself. Some substations have experienced multiple incidents within a year, mostly caused by human factors, seriously affecting the overall operation of the substation. Therefore, in order to prevent this situation from happening, firstly, it is necessary to establish a system for the operation and management of the substation's backend monitoring machine and strictly enforce it. The on duty personnel should be restrained to prevent the use of the backend monitoring machine to play games or surf the internet, and to prevent the unauthorized use of floppy disks and CDs to infect the monitoring machine with viruses. Once the backend monitoring machine is paralyzed due to human reasons, it should be strictly punished according to the system, and not tolerated. At the same time, others should be warned. The second is to strengthen the regular and irregular inspections of the county bureau management department, identify problems, handle them immediately, and leave no future troubles. The third is to establish password management measures for the operating system and monitoring software. Only the county bureau management department and the substation master have access to the password, and ordinary duty personnel do not have access to the password. This is to prevent unauthorized access to the operating system and the startup and shutdown of monitoring software, as well as to prevent the use of software and hardware resources of the background monitoring machine and their destruction. The fourth is to package the operating system with monitoring software, such as the backend monitoring software of Dongfang Electronics' DF1331 automation system, which has the function of encapsulating the operating system after startup. The encapsulation of the monitoring software operating system refers to the automatic startup of the monitoring software when the background monitoring machine is first started, and then continues to start the monitoring software until it reaches the monitoring software interface. If the monitoring software is stopped, a password needs to be entered, and only those who master the password can stop the monitoring software and enter the operating system. At present, some backend monitoring software of substation automation systems do not have this function, which should be resolved jointly with the manufacturer's technical personnel. The encapsulation of operating system functions in monitoring software is very effective in preventing the background monitoring machine from being used and damaged by others. When choosing backend monitoring software, attention should be paid to selecting products with this function to improve the safety and reliability of the backend monitoring system operation.
2.1.3 The background monitoring machine should choose an industrial control computer
Due to the requirement of real-time operation, large data processing capacity, fast response speed, and strong electromagnetic environment of the background monitoring machine, ordinary computers cannot meet the requirements. Therefore, high-performance industrial control computers should be selected when choosing. High performance industrial control computers can operate in strong electromagnetic environments, have strong anti-interference performance, can run in real-time, have good hardware device stability, and can meet the requirements of substation backend monitoring systems. At present, in some substations, due to the extensive use of commercial, household, and other computers in the background monitoring machines, there have been cases where the background monitoring machines are damaged and unable to work. High performance industrial control computers can ensure the safe and stable operation of the substation backend monitoring system.
2.1.4 The backend monitoring machine should be equipped with an uninterruptible power supply
In some substations, there is no uninterruptible power supply configured for the background monitoring machine, and the station's AC power supply is used instead. There are the following drawbacks to using station transformer AC power supply: firstly, when the system loses power, the background monitoring machine loses power and cannot work; The second issue is that the AC voltage of the occupied transformer fluctuates greatly, and the voltage quality is sometimes not up to standard. Sometimes the voltage is high, causing the computer to burn out. Sometimes the voltage is low, causing the computer to malfunction and unable to provide qualified power to the backend monitoring machine; Thirdly, when the primary fuse of the station transformer blows, the backend monitoring machine loses power; Fourthly, when the 10kV system is grounded, the AC power supply of the station transformer is severely affected by harmonic interference, which affects the normal operation of the background monitoring machine. At present, some manufacturers produce DC inverter AC inverters, which use on-site DC batteries as the DC power source for the inverters. After inverting the AC power, it is supplied to the background monitoring machine for use, with a capacity of 500-1000VA. Configuring this inverter eliminates the need to purchase additional DC batteries, saving investment and achieving good results.
2.1.5 Real time data and accident records cannot be stored in the backend monitoring system
At present, the backend monitoring system of some substation automation systems cannot store real-time data and accident records. With the continuous development of hard disk manufacturing technology, large capacity hard disks have emerged and been widely used. Monitoring software should have the function of storing real-time data at optional time intervals, and should have the function of storing accident records for easy saving, searching, browsing, and printing of historical data and accident records.
2.2 Protection monitoring system does not have fault filtering device
At present, some substations' protection monitoring systems do not have fault filtering devices. As a substation automation system, the fault filtering device should be an essential device. When the distribution line trips due to a fault, the fault filtering device can record the changes in current and fault current values within 10 or more cycles before and after the fault trip, making it easy to analyze the cause of the fault.
2.3 Protecting the accident and warning audio signals of the monitoring system
The accident and warning sound signals of some substations' protection monitoring systems are controlled by the backend monitoring system. When the backend monitoring machine cannot work, the accident and warning sound signals cannot be sent out, and the duty personnel cannot be prompted to handle the accident or fault, seriously affecting the safe operation of the substation. This situation has occurred several times, causing PT burnout and unknown switch accidents and tripping. For this situation, it is necessary to contact the manufacturer to jointly handle and separate the accident and warning sound signals of the protection monitoring system, which are not controlled by the background monitoring system, to prevent the occurrence of situations where the background monitoring machine cannot send out protection accidents and warning sound signals when it is not working.
2.4 Transmission and reception processing of remote control data and information in the protection monitoring system
2.4.1 Transmission of Remote Control Data and Information
The remote control data and information of some substation automation systems are sent to the dispatch master station through the background monitoring system. When the background monitoring system cannot work normally, the transmission of remote control data and information cannot be sent. This method is not conducive to the transmission of remote control data and information, and should be directly sent to the dispatch master station through the communication unit of the protection and monitoring system, without being controlled by the background monitoring system. Due to the control of the backend monitoring system for the transmission of remote data and information, several substations have stopped sending remote data and information to the dispatch master station due to the malfunction of the backend monitoring machine. This situation can only be handled by the manufacturer.
2.4.2 Remote control data and information transmission, reception and processing
At present, some substation automation systems have weak capabilities in sending, receiving, and processing remote control data and information, mainly manifested in the inability to upload protection settings, main transformer gears, etc., and the inability to correctly receive and process functions such as switch remote control operations, modification of settings, and main transformer gear adjustment of the dispatch master station. Due to the existence of this issue, the automation level of substations is greatly affected, which is not conducive to remote operation of equipment.
3 Summary
The above problems are some of the more serious issues that arise in the actual operation of substation automation systems. Some can be handled by themselves, while most require manufacturers to handle, and some cannot be handled by manufacturers. The existence of these problems is not conducive to the safe, reliable, and stable operation of substations. When choosing a substation automation system, attention should be paid to whether the above issues exist and whether the overall functionality of the substation automation system is complete. The substation automation system is the core of the substation, and choosing a high-quality substation automation system is crucial for the safe, reliable, and stable operation of the substation.