Talking about the performance and maintenance measures of relay protection [20 10-06-27 03:08]. The relay protection device is an important equipment related to the safe and stable operation of the power grid, an indispensable part of the power system and the third line of defense for the safe and stable operation of the power grid. In this paper, the reliability characteristics of relay protection and automation devices are studied preliminarily. This paper analyzes the present situation of relay protection and the main problems existing in relay protection inspection, and probes into the maintenance measures of relay protection under the new situation.

Keywords: relay protection; Reliability; Maintenance measures

In recent years, with the development of computer technology and communication technology, the principle and technology of power system relay protection have changed greatly. Reliability research is an important factor in relay protection and automation devices. With the increasing capacity of power system, wider power supply range and more complex system structure, the reliability of relay protection is particularly important, so it is necessary to study and discuss the reliability of relay protection. In view of the importance of relay protection, it is absolutely necessary to carry out preventive tests on it regularly, and it must not be analyzed and repaired after incorrect actions appear. Therefore, the maintenance strategies and measures of relay protection are also very important. This paper discusses this problem based on my years of work experience.

1, factors affecting the reliability of relay protection

Relay protection device is an automatic device, which plays an important role in ensuring the safe and reliable operation of power system. When the system is abnormal, the relay protection device will send a signal to the personnel on duty to remind them to take timely measures to eliminate the fault and restore the normal operation of the system. After the relay protection device is put into operation, it enters the working state, correctly performs the protection function according to the given setting value, constantly monitors the change of the running state of the power supply system, and acts correctly when there is a fault, so as to remove the fault. When the power supply system operates normally, the protection device does not act. There are two intact States of "correct action" and "correct inaction", which shows that the protection device is reliable. If the "misoperation" of the protection device occurs during the normal operation of the protected equipment or the failure of the protected equipment, but the protection device "refuses to operate or has no selective action", it belongs to "incorrect action". As far as the power system is concerned, the "misoperation or non-selective action" of the protection device is not terrible, and it can be corrected by automatic reclosing. Horribly, the "refusing action" of the protection device has a wide range of effects and may lead to the collapse of the power system. The abnormal operation of relay protection may have the following reasons.

(1) relay protection device manufacturers did not strictly carry out quality management in the production process to ensure good quality.

(2) The operation of the relay protection device is greatly influenced by the surrounding environment. Because there are a lot of dust and harmful gases in the surrounding air and affected by high temperature, it will accelerate the aging of relay protection devices and lead to performance changes. Harmful gas will also corrode the circuit board and socket, so that the relay contacts will be oxidized, resulting in poor contact and loss of protection function.

(3) The transistor protection device is easily influenced by interference sources, such as arc, lightning circuit, short circuit fault and many other factors, which lead to misoperation or refusal to operate.

(4) The reliability of protection depends to a great extent on the safety awareness, skills and sense of responsibility of operation, maintenance and repair personnel. The reliability of relay protection is closely related to the debugging personnel, such as low technical level, little experience, weak sense of responsibility and poor ability to find and deal with existing problems.

(5) The quality of the transformer is poor, and the working characteristics change in long-term operation, which affects the working effect of the protection device.

(6) The way and superior-subordinate protection adopted in the protection scheme are unreasonable and the choice is improper.

2, measures to improve the reliability of relay protection

It runs through the whole process of relay protection design, selection, manufacture, operation and maintenance, setting calculation and setting debugging. The reliability of relay protection system mainly depends on the reliability of relay protection device and the rationality of design. Among them, the reliability of relay protection device plays a key role. After the protection device is put into operation, it will be affected by many factors and cannot be absolutely reliable. However, as long as all kinds of accident prevention schemes are formulated and corresponding effective preventive measures are taken to eliminate hidden dangers and make up for deficiencies, its reliability can be realized. Measures to improve the reliability of relay protection should pay attention to the following points:

(1) In the manufacturing process of protection devices, the quality should be well controlled, and the overall quality level of the devices should be improved. Components with low failure rate and long service life should be selected, and unqualified inferior components should not be mixed. At the same time, when choosing equipment, try to choose manufacturers with good quality and good after-sales service.

(2) When designing the transistor protection device, it should be installed in a room isolated from the high voltage room to avoid the influence of high voltage and high current, open circuit fault and switching operation arc. At the same time, it is necessary to prevent environmental pollution to transistors, and air conditioning should be installed if possible. Rubber gasket should be sealed between the shell and base of electromagnetic and electromechanical relay to prevent dust and harmful gas from invading.

(3) The professional and technical personnel of relay protection should enhance the sense of responsibility of setting calculation. When calculating, the whole network should be considered and carefully analyzed, so that the setting values of all levels of protection are accurate and the setting values of upper and lower protection are reasonable.

(4) Strengthen the operation, maintenance and fault handling capacity of protection devices, conduct regular inspections and formulate anti-accident measures to improve the reliability of protection devices.

(5) Considering the dynamic stability of the power system, the relay protection system is required to have the ability to quickly remove faults. Therefore, the main protection of important transmission lines or equipment adopts a variety of facilities, and two sets of main protection need to run in parallel.

(6) In order to make the protection device act selectively and avoid non-selective action when the fault occurs, the design and setting calculation of the protection device should be comprehensively considered, and the components should be reasonably matched to improve the reliability of the protection device. 3. Maintenance strategies and measures of relay protection under the new situation.

In view of the importance of relay protection, it is absolutely necessary to carry out preventive tests on it regularly, and it must not be analyzed and repaired after incorrect actions appear. The fundamental purpose of regular maintenance of relay protection should be "to ensure that the whole relay protection system is in good condition and can ensure the safety and reliability of the action". Therefore, in principle, the planned inspection items should be obviously different from the newly installed items, and only a small number of targeted tests can be carried out. Attention should be paid to projects that have a significant impact on the safety and reliability of protection actions, and maintenance for the sake of maintenance should be avoided, so as to obtain the maximum return on the investment benefit of periodic inspection of protection. Suggest the following points:

(1) Study new problems under the new situation as soon as possible, formulate new maintenance strategies, revise relevant regulations (for a large number of non-individual phenomena, it is not appropriate for the operating unit to approve them by itself), guide the current and future relay protection inspection work, actively carry out state maintenance of secondary equipment, "loosen" relay protection personnel, and minimize the impact of maintenance on system safety and relay protection availability.

(2) When making the maintenance strategy, we should combine the self-inspection and communication ability of microcomputer protection, strive to improve the reliability and safety of the protection system, simplify the maintenance of the device, and attach importance to the inspection of the secondary circuit.

(3) The design of secondary circuit should be simplified in the future; Strengthen maintenance and basic management in operation, pay attention to the accumulation of operation data, especially pay attention to the statistics, analysis and processing of equipment failure information, so that maintenance is based on scientific statistical data; In capital construction, we should strengthen power grid construction and relay protection transformation, and attach importance to equipment selection, so as to improve the overall level of relay protection system and create conditions for implementing new strategies.

(4) Vigorously carry out on-line monitoring of secondary lines, and study the maintenance technology of relay protection system without power failure.

(5) With the development of substation integrated automation, the development direction of distributed arrangement of protection devices, centralized processing, networking between devices, optical fiber relay protection operation and protection inspection after the completion of fault information network is studied.

(6) The manufacturer should further improve the self-checking ability of microcomputer protection and the output ability of device fault information, and develop new protection that meets the requirements of remote detection protection devices.

4. Conclusion

This paper discusses the reliability of relay protection devices in power supply system, and puts forward the necessity of discussing the reliability of relay protection, the factors affecting the reliability of relay protection and the countermeasures to improve the reliability of relay protection. Its reliability is not only closely related to design, manufacture, operation and maintenance, overhaul and debugging, but also the maintenance personnel of relay protection devices will play a key role. Finally, the purpose of protection inspection is discussed, and it is suggested that relevant laws and regulations should be revised as soon as possible, and the maintenance strategy of relay protection under the new situation should be studied and formulated.

refer to

GB50062292。 Code for design of relay protection and automatic device of power equipment [Z]. Beijing: China Planning Press. 1992.

[2] JJ/T 16292。 Code for electrical design of civil buildings [z]. Beijing: China Planning Press. 1994.

[3] Zhao Zigang, Yan Xiaoding. Analysis of problems existing in relay protection inspection. Power grid technology: ~ 1998. ( 10): 19 ~ 2 1,25.

Shen ... Test method of relay protection secondary circuit [J]. Jilin Electric Power, 2008? 6? 136 ( 1).