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This post was last edited by chenjinfeng on February 7, 2020, at 16:56. This paper analyzes the application and deactivation of microcomputer-based five-prevention systems. It also elaborates on the necessary integration of such systems with electrical five-prevention measures. Furthermore, it proposes a key integrated solution for preventing misoperations by combining microcomputer-based and electrical five-prevention systems. This solution is of great significance for the design, construction, and operation of both newly commissioned substations and existing ones in terms of their microcomputer-based error-prevention and locking system upgrades. Microcomputer-based five-prevention system, electrical five-prevention measures, operations, and delocking: 1. Requirements set forth by substation operation safety management regarding error prevention. In light of numerous lessons learned at great cost, and drawing on both domestic and international practices in electrical operations, the power system has established measures to effectively prevent personal injuries and major equipment accidents caused by operational errors involving electrical equipment. Such errors can be attributed to three groups of people: 1) operating shift personnel, 2) maintenance workers, and 3) other individuals. To prevent misoperations by operators. These incidents mainly occur due to incorrect pulling or closing of circuit breakers and switches, open circuits, or accidental entry into switchgear compartments; such situations can easily lead to serious accidents. Microcomputer-based anti-misoperation systems are proactive measures taken to prevent such accidents. They fulfill the requirements for preventing misoperations during switch operations, based on the substation expert system. But it is implemented on a microcomputer and is virtual. It can only meet the operational requirements of operating duty personnel; it cannot completely prevent misoperations by maintenance personnel and other individuals. To address mistakes made by maintenance personnel. It mainly occurs during maintenance and testing, when operators perform no actions whatsoever. Since the microcomputer-based anti-misoperation system cannot cover all operations at substations, especially those performed by maintenance personnel, it is crucial not to rely entirely on the microcomputer for preventing misoperations. In such circumstances, when one cannot entirely rely on microcomputer-based anti-mistake systems, electrical circuit interlocking becomes the last line of defense for safety. To prevent accidental operations by other personnel. Primarily refers to personnel who have no relation to normal operations. Such situations are relatively rare, but they do occur from time to time. When uninvolved persons are near the control panel or mechanism box, accidental contact is very likely to occur ； This can lead to misoperation accidents, a problem that microcomputer-based anti-misoperation systems cannot resolve effectively. 2 Traditional anti-misoperation interlocks and modern microcomputer-based five-prevention technologies Principles and applications of traditional electrical anti-misoperation systems. The five prevention functions refer to ① preventing accidental opening and closing of circuit breakers. ②Prevent opening and closing of disconnectors under load. ③Prevent connecting (closing) grounding wires (ground switches) while the equipment is energized. ④Prevent closing the circuit breaker (isolator) when the grounding wire (grounding switch) is attached. ⑤Prevent accidental entry into live compartments. Traditional electrical interlocking is an anti-mistake function based on secondary operating circuits; it is generally implemented through the interlocking of auxiliary contacts of switches. Principles and applications of microcomputer-based five-prevention technology. Microcomputer-based five-prevention is a device that utilizes computer technology to prevent electrical misoperations in high-voltage switchgear. It generally consists mainly of functional components such as a host, an analog panel, a computer key, and a mechanical coded lock. The equipment that is locked by currently used microcomputer-based anti-misoperation locking devices includes circuit breakers, switches, grounding wires (grounding switches), and barrier gate doors (switchgear doors). These devices are locked via microcomputer locks (electrical coded locks and mechanical coded locks); therefore, software must be developed to define the locking rules for them. Comparison between microcomputer “five prevention” and electrical anti-misoperation technologies. The electrical anti-misoperation interlock circuit is a field electrical interlocking technique that primarily achieves interlocking through the auxiliary contacts of related equipment. This is the most basic form of electrical interlocking; it is reliable. However, this approach requires the use of a large number of secondary cables, the wiring is relatively complex, and operation and maintenance are difficult. Microcomputer-based five-prevention systems generally do not use the auxiliary contacts of field devices; the wiring is simple, and error prevention locking is achieved through the rule database of the microcomputer software in the five-prevention system and the on-site locks. Electrical interlock circuits can generally only prevent incorrect operation of circuit breakers, isolators, and grounding switches; they are ineffective against situations such as entering live compartments by mistake or connecting (removing) grounding wires, and thus cannot achieve complete \"five-prevention\" protection. The microcomputer-based five-prevention system can develop corresponding \"five-prevention\" rules based on the actual conditions on site, thereby enabling relatively comprehensive \"five-prevention\" functions. Only when the lockout is lifted before the microcomputer system fault has been resolved does the five-prevention function become completely lost. Additionally, the microcomputer-based five-prevention system also has the problem of misoperations caused by \"missing steps\" (omitting certain actions during the operation process). 3. Robust error-prevention solutions: Electrical interlock circuits have been continuously improved over the course of the development of power systems. However, in large substations with complex circuit layouts and numerous compartments, the use of a large amount of cable is required to implement such circuits. During operation, issues such as unreliable switch auxiliary contacts and damage-prone outdoor electromagnetic lock mechanisms arise. Furthermore, their error-prevention capabilities depend on the secondary wiring, making it difficult to add or modify these functions, and thus complete five-layer error prevention cannot be achieved. 4 Traditional anti-misoperation interlocking and modern microcomputer-based five-prevention technologies The traditional electrical interlocking circuits and the first-generation microcomputer-based five-prevention systems each have their own characteristics. For newly built or renovated substations, it is recommended to adopt the following five-prevention system solutions: Solution 1: For substations (hereinafter referred to as the station), if the positions of all circuit breakers and switches are monitored via real-time remote signaling, and if the microcomputer-based five-prevention system shares a database with the station’s monitoring system, it may be possible to omit or eliminate the use of electrical interlocking circuits. All anti-misoperation functions can then be handled by the microcomputer-based five-prevention system alone; it is also necessary for this system to have measures in place to prevent unauthorized operations. Option 2: For substations where the positions of all circuit breakers and switches are represented by virtual remote signals, and where the microcomputer-based interlock system and the substation monitoring system share a single database, it may be possible to omit or eliminate the electrical circuit interlocks (referring mainly to the electromagnetic locks of the grounding switches and the comprehensive interlocks); in such cases, the error-prevention functions will be carried out by both the microcomputer-based interlock system and the electrical interlock circuits of the switchgear. The microcomputer-based five-prevention system is required to have anti-air intrusion measures. Option 3: Regardless of whether the positions of all circuit breakers and switches in the substation are represented by virtual remote signals or real remote signals, and regardless of whether the microcomputer-based interlock system and the substation monitoring system share a single database, no electrical circuit interlocks are designed or removed; instead, microcomputer-based interlock contacts are added to the operating power circuits of the electrically operated switches or grounding switch mechanisms, with the error prevention function being carried out independently by the microcomputer-based interlock system. The microcomputer-based five-prevention system is required to have anti-air intrusion measures. 5. Integration scheme of microcomputer-based five-prevention measures and electrical five-prevention measures Designers believe that with the use of microcomputer-based five-prevention measures, there is no need to consider electrical five-prevention circuits any longer; therefore, substations equipped with prefabricated high-voltage switchgear do not have such electrical five-prevention circuits in the initial stage of implementing microcomputer-based five-prevention measures. Additionally, in substations where microcomputer-based five-prevention measures are implemented by modifying existing electrical or mechanical interlocks, due to the numerous issues associated with electrical five-prevention circuits previously, these circuits are either short-circuited or removed during the transformation process. The 4.13 accident that occurred in Shaoyang, Hunan, mentioned in the introduction of this article, was caused by maintenance workers closing the busbar disconnect switch while it had not been opened. When electrical five-prevention measures are in use, the operating power supply for the busbar disconnect switch is locked by the auxiliary contacts of the bus coupler switch, thereby preventing accidents. With the microcomputer-based five-prevention system, once unlocking is achieved, as long as the door of the operating mechanism is opened, there is no locking in place for subsequent operations, and this is precisely the root cause of accidents. This paper argues that the critical electrical interlock relationships should not only be maintained but also strengthened, so that in the event of a lockout, these electrical interlocks can serve as a second line of defense. For example: the electrical interlock relationship between the busbar disconnect switch and the busbar grounding switch, etc. This article argues that emphasis should be placed on preventing certain types of operational errors that pose significant risks and occur frequently. According to statistics, the frequency of errors involving the accidental closing of busbar disconnect switches while the busbar grounding switch is in use is relatively high. The reason for this is that there are many issues with these disconnect switches in high-voltage switching equipment, such as problems with their ability to open and close or incomplete operation. Identifying and addressing these issues usually takes place during power outage or restoration procedures, and this inevitably leads to an increase in workload. Especially during power restoration, there is a rush to complete the process, and there is hesitation to report any problems (as this could result in penalties or affect the availability of the equipment). As a result, instructions from higher authorities are often ignored, and this issue needs to be addressed urgently.