1 Introduction
By introducing intelligent components and new technologies, the intelligent substation improves the intelligent level of each equipment and the automatic regulation ability of the substation system, so that each equipment in the substation has the function of independently performing relevant tasks, and each module of the whole system is relatively independent and has good cooperation ability. For example, the adoption of electronic transformer improves the equipment measurement and monitoring ability, and the adoption of intelligent components improves the equipment analysis and control ability. Based on these technologies, real-time detection and remote regulation of substation are possible, and the flexibility and efficiency of the system are significantly improved.

In addition, through the digital signal analysis technology, the relevant detection technology of each equipment is unified into the digital signal of the standard interface, so as to realize the interconnection of signals between each equipment and enhance the coordination ability of the system. Due to the obvious advantages of intelligent substation compared with traditional substation, intelligent substation has been widely popularized and applied in power grid. With the advance of intelligent substation operation, some problems are increasingly exposed, which need to be overhauled and maintained in the process of operation. This paper will summarize the main problems existing in the operation of intelligent substation, and put forward relevant countermeasures for operation and maintenance safety control.

2 common problems in operation and maintenance of Intelligent Substation
Installation protection issues. In order to reduce the number of cables in the substation and improve the operation safety of the substation, the intelligent substation has installed protection equipment near the primary equipment. At present, the commonly used protection equipment here is mainly intelligent centralized control cabinet. However, the protection equipment has certain requirements for the external environment. When the relative humidity of the environment exceeds 90% or the temperature is lower than minus 25 ℃, corresponding auxiliary equipment needs to be added. The installation of auxiliary equipment will increase the workload and cost of future maintenance.

Fast protection issues. With the introduction of electronic transformer, the integration of intelligent substation has been greatly improved. However, in the information transmission process of electronic transformer, due to the large number of integrated equipment involved, the merging operation of multiple units is required, which delays the transmission rate to a certain extent. In addition, in the intelligent substation, the operation of combined units such as optical fiber transmission and intelligent terminal also has the problem of prolonging the transmission time. Therefore, in the process of protection action, compared with the traditional substation, the intelligent substation should be extended by 5 ~ 7ms.

Reliability issues. In order to ensure the uninterrupted operation of electronic transformer and other communication equipment, it is necessary to install active electronic components for uninterrupted power supply. The installation of these active equipment will interfere with the communication to a certain extent, especially when the temperature in the external environment changes greatly, which will reduce the reliability of optical fiber transmission.

Security issues. Due to the obvious improvement of integration, the communication of intelligent substation is also changed from point-to-point communication of traditional substation to multipoint communication. Although the communication efficiency is higher, the security is relatively low. As long as a node in the communication system is damaged or fails, the whole communication network will be paralyzed. Therefore, in the process of operation and maintenance, communication security needs to be focused.


3 Analysis of operation and maintenance security control strategy of Intelligent Substation

3.1 strengthen safety management
For the operation and maintenance safety control of intelligent substation, the safety management mainly includes the following two aspects:
Establish a complete operation and maintenance safety control responsibility system. System is the key to ensure the smooth and orderly progress of operation and maintenance. In order to ensure the safety control of operation and maintenance of intelligent substation, first of all, a detailed and scientific responsibility system is required, including the subdivision of operation and maintenance tasks and the implementation of safety responsibilities, so that tasks and responsibilities are assigned to people. For the situation that the tasks and responsibilities are not implemented in place, it is necessary to provide reasonable punishment measures. For the employees who complete the tasks and responsibilities well, it is necessary to establish supporting incentive measures. On the one hand, establish the safety bottom line awareness for all employees, on the other hand, fully mobilize the enthusiasm of all employees and take the initiative to eliminate the potential risks that may exist in the process of operation and maintenance.

Strictly implement the "two votes and three systems". After years of operation practice, "two tickets and three systems" is an effective measure to ensure the safety of operation and maintenance. In the process of operation and maintenance management of intelligent substation, it is also necessary to strictly implement the "two tickets and three systems", which can not only ensure the reasonable arrangement of various safety measures, but also eliminate potential risks. Ensure the operation and maintenance quality and improve the safety of operation and maintenance personnel and equipment through strict operation and maintenance system.


3.2 strengthen patrol management

Patrol management is an important part of operation and maintenance safety control. Strengthening patrol management can focus on the following three aspects:





Strengthen daily patrol management. Intelligent substation is the integration of a large number of intelligent devices, and the relevant intelligent devices have high requirements for the operating environment. The natural environment is more complex, especially there will be some extreme weather, which makes the relevant intelligent devices operate under conditions other than the set conditions, which will undoubtedly bring certain potential safety hazards, and in serious cases, it may also cause equipment damage or power grid accidents. In order to eliminate such problems, we need to focus on the daily inspection of intelligent substation to ensure the effect of daily inspection. In particular, the key equipment needs to be inspected and calibrated regularly to find problems in advance and eliminate hidden dangers.





Joint patrol management. As the structure of intelligent substation is relatively complex, and the operation and maintenance personnel are limited by their knowledge, it is difficult to make a comprehensive inspection in the process of daily inspection. Therefore, in order to improve the overall operation safety of intelligent substation, it is necessary to regularly organize joint inspection, and the inspection technicians from all aspects shall jointly investigate the potential hazards.





Return visit management. Intelligent substation is highly integrated, and a large number of equipment are produced and operated by manufacturers. For such equipment, it is necessary to establish a regular return visit management system, and timely communicate and return visit with the equipment manufacturer according to the operation status of the equipment, so as to eliminate potential risks.





3.3 strengthen personnel training management





The key to the operation and maintenance safety control of intelligent substation lies in the relevant staff. It is very important to strengthen the training management of these personnel. Intelligent substation integrates a large number of new technologies, which puts forward higher requirements for the corresponding operation and maintenance personnel. On the one hand, it is necessary to strengthen the professional knowledge training of relevant operation and maintenance personnel to master the operation principle, common faults and fault diagnosis and treatment measures of each module of intelligent substation. On the other hand, it is necessary to establish a solid safety awareness for the staff. Only by strengthening the safety awareness of operation and maintenance personnel can we further improve the operation and maintenance quality of intelligent substation and eliminate all kinds of potential safety hazards. In order to ensure the training time and quality, it is necessary to establish corresponding training mechanism to strictly guarantee the training duration and training expenditure of each employee.





3.4 strengthen equipment management





The safe operation of intelligent substation is the result of the cooperative operation of many equipment, involving many equipment, including transformer and various terminals. Therefore, it is necessary to strengthen the management of equipment in operation and maintenance safety control. Firstly, in order to improve the pertinence of operation and maintenance of various equipment, it is necessary to establish a database of various equipment to record the operation status of the equipment in detail, the possible fault types of such equipment, the diagnosis methods of corresponding faults and the treatment measures of various faults, so as to predict the potential risks of the equipment in advance and take preventive measures to improve the effect of operation and maintenance.





Secondly, strengthen the operation and management of equipment. Including sequence control operation ticket management, switching operation ticket management, operator management and substation "five prevention" requirements. Carry out corresponding operation management in strict accordance with the working characteristics of various equipment, so as to ensure that all operations have rules to follow and all operators are skilled.





Finally, strengthen remote patrol management. Intelligent substation is equipped with a large number of communication facilities, visualization facilities and online monitoring facilities, so a large number of patrol work can be realized by remote means. Remote inspection has become one of the important contents of intelligent substation operation and maintenance management. On the one hand, it can further improve the monitoring performance of the intelligent monitoring platform and realize the intelligent monitoring and diagnosis of various faults; On the other hand, it is necessary to improve the professional skills of remote patrol personnel and their ability to deal with various complex problems.





4 Conclusion





As an important part of the power grid, the safe and stable operation of the smart substation is directly related to the power supply safety of the power grid. Therefore, strengthening the operation and maintenance management of the smart substation is of great significance and has become one of the important contents of the operation and maintenance management of the power grid. In order to further improve the operation and maintenance safety control of intelligent substation, we can strengthen the construction of safety system, strictly implement the "two tickets and three systems", strengthen daily patrol management, joint patrol management and return visit management, strengthen the training of skills and safety awareness of operation and maintenance personnel, and strengthen equipment management.
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