Electrical misoperation refers to the erroneous result that the electrical staff is paralyzed or violated the regulations when performing the operation, and accidentally touches the equipment against the will of the operation instruction. Once misoperation occurs, it will cause personal and equipment accidents, resulting in greater economic losses.
The electrical misoperations that occur in the operation of photovoltaic power plants mainly include:
(1) Prevent the circuit breaker from being disconnected or closed by mistake.
(2) Prevent the contact of the disconnector or handcart from being pulled or closed with load.
(3) Prevent the ground wire (ground isolation switch) from being hung (closed) with electricity.
(4) Prevent the circuit breaker (isolating switch) with the ground wire (ground isolating switch).
(5) Prevent from entering the live interval by mistake.
In the operation and maintenance practice of photovoltaic power plants, the “five preventions” functions of safety production must take mandatory measures to prevent electrical circuit breakers from being mis-opened and closed due to technical reasons. Malpractice measures. The so-called mandatory measures to prevent electrical misoperation refer to: connect the power connection or lock controlled by the blocking circuit in series in the electric operation control circuit of the equipment, and install the lock controlled by the blocking circuit on the manual control part of the equipment (five anti-locks), At the same time, avoid idling operations as far as possible according to the requirements of technical conditions.
The safety production of the power station prevents electrical misoperations by adding five anti-locks to the high-voltage switchgear (see Figure 1), which are used to force the operators to operate the electrical equipment correctly in accordance with the established safe operation procedures, thereby avoiding misoperation accidents. occur. There are four main types of conventional anti-mistake locking methods for photovoltaic power plants: mechanical locking, program locking, electrical interlocking and electromagnetic locking.
The realization of electrical “five defenses” has become one of the important measures for electric power safety production. With the continuous development of the power grid and the continuous updating of technology, the anti-error device has been continuously improved and perfected (see Figure 2 for the “five-proof” control system, and Figure 3 for the intelligent management machine). The design principle of the anti-misoperation device is: any high-voltage electrical equipment that may cause misoperation should be equipped with an anti-misoperation device and a corresponding anti-misoperation electrical locking circuit.
- General requirements to prevent electrical misoperation
In order to prevent the occurrence of electrical misoperation incidents, the photovoltaic power station should formulate a management system to prevent electrical misoperation, and formulate various technical measures to prevent electrical misoperation on site. The “microcomputer five-proof locking device” of the power station must be safe and reliable, put into operation normally, and must not be shut down without permission. In special circumstances, the shutdown must be approved by the operation and maintenance management department and recorded. In addition, to prevent electrical misoperation and safe production, the following requirements should also be met:
1) Strictly implement the standardized management of “two votes” and strengthen the operation monitoring system.
2) For major electrical operations such as power outages for the entire station and main transformers, the person in charge of the power station or safety technicians must go to the site to supervise and direct to prevent electrical misoperation accidents.
3) Safety tools such as insulating rods, insulating clapboards, insulating gloves, insulating boots, electroscopes, and portable short-circuit grounding wires must be managed and tested regularly. If the test is qualified, the certificate of qualification should be pasted, and it should be carefully checked before use to ensure that the tools are in good condition.
4) The mechanical and electrical indications of the position and status of circuit breakers, isolating switches, and grounding isolating switches should be accurate and clear.
5) All portable short-circuit grounding wires on site must be numbered, seated according to the voltage level, stored in the designated place, and handed over according to the value. When using, the work ticket, operation ticket, simulation board, grounding device announcement board and shift diary must be completely corresponded.
6) The portable short-circuit grounding wire must be installed to ensure reliable contact of each part, and the cross-sectional area of the short-circuit grounding wire must meet the standard. Wires, wire clips, and wire sheaths must meet the standards, the fixing screws should not be loosened, and the grounding wire signs and test certificates should be clear and not fall off.
7) Standardize the storage of emergency unlock keys, strictly use the approval process, and keep records of use. All kinds of keys should be managed by fixed placement, and the registration records of use and borrowing should be established.
8) Strengthen the training of employees on anti-mistake locking devices, and often organize special anti-accident activities.
Second, the main measures to prevent electrical misuse
During the switch-off operation, in order to prevent the occurrence of mistakenly pulling, mistakenly closing the circuit breaker and isolating switch, the operator must be correct and clear in issuing the command, receiving the command or contacting the switch-off operation, and insist on repeating it repeatedly, and recording if possible. Before the operation, carry out the “three comparisons”, adhere to the “three prohibitions” during the operation, and insist on re-examination after the operation, and implement the “five nos” throughout the operation.
“Three comparisons”, that is, to compare the operation tasks, operation modes, and the operator to fill in the operation ticket; compare the five-defense simulation diagram, review the operation ticket term; compare the equipment number before operation.
“Three prohibitions”, that is, the operator and the guardian are forbidden to operate together and lose their guardianship (if there is an operation that cannot be completed by one person during the operation, the guardian can assist the operation after confirming that it is correct); it is forbidden to operate blindly when in doubt; it is forbidden to operate while Distracted while doing other unrelated operations or chatting.
“Five do not do”, that is, do not do if the operation task is unclear; do not do it when there should be an operating ticket but no operating ticket; do not do it if the operating ticket is not qualified; do not do it if there is a guardianship; do not do it without a guardian;
Through daily training (on-site examination room, explanation of typical cases, anti-accident drills, etc.), operation and maintenance personnel can improve their safety awareness, master the correct operation methods, and improve the correctness of electrical operations. Before carrying out major operations and special changes in operation methods, operators should analyze dangerous points in advance, formulate and implement safety technical precautions in a targeted manner, and do a good job in accident prevention. When the operator has doubts in the electrical operation, he should immediately stop the operation and ask the person on duty and the safety technical supervisor to clarify the operation later. The occurrence of dangerous misoperations such as pulling and closing the disconnector with the load, installing the grounding wire or closing the disconnecting switch with live electricity.
- Measures to prevent pulling and closing isolating switches with load
Dianranfagor’s production implements standardized management in the operation circle, strictly implements the operation system, and operates correctly item by item in accordance with the wind sequence in the operation ticket, without skipping items or missing items.
When the background machine of the network computer monitoring system fails and cannot be operated remotely, it should obtain the consent of the person in charge of the duty and the safety technical supervisor, and strengthen the operation monitoring when changing to local operation. Carefully check the name and number of the equipment to prevent wrong interval, wrong Pull or close the isolating switch by mistake, and at the same time ensure that the anti-misoperation locking device installed on the isolating switch and the grounding isolating switch is put in correctly. When the network computer monitoring system is running normally, it must be simulated on the five-proof machine before it can be operated on the background machine. It is forbidden to force the unlocking of the background machine to operate; the operation of the background machine must also comply with the operation monitoring system; All isolating switches have been closed. Before pulling the isolating switch, it must be checked that the corresponding switch is disconnected. - Measures to prevent live installation of grounding wires or grounding isolating switches
When the circuit breaker and isolating switch are opened, check the actual position and status on the spot to confirm that they have been opened, so as to prevent the circuit current from being cut off. Before installing the grounding wire or closing the grounding isolating switch, you must conduct an electrical inspection carefully, and after confirming that there is no voltage, operate the isolating switch to open it. Causes a short circuit. Special attention should be paid to the isolating switch with grounding isolating switches on both sides. Once the isolating switch is opened, the mechanical locking of the grounding isolating switch has no effect. At this time, any group of grounding isolating switches can be freely closed. . - Measures to prevent the disconnector and disconnector with ground wire or grounding disconnector from closing
In the daily operation and production, the operation and maintenance personnel should strengthen the management of the ground wire, use the numbered ground wire, and register it. When installing or dismantling the ground wire or pulling and closing the isolating switch and grounding isolating switch, it should be recorded in the work log, and it should be consistent with the actual position on the site. Is it consistent. It is strictly forbidden to install or remove the ground wire, move the position of the ground wire or increase the number of ground wires on the equipment system without the consent of the person in charge on duty. Special attention should be paid to the isolation switch that may be powered to the maintenance site once operated, the operating mechanism should be locked, and the safety sign “prohibit closing, no one is working” should be hung.
After overhauling the equipment, it should be noted that the isolation switch after overhaul should be kept in the off position to avoid connecting the ground wire of the overhaul circuit and causing a short circuit during power transmission; to prevent tools, instruments, ladders and other objects from being left on the equipment and power transmission. cause a short circuit. Before power transmission, the insulation resistance of the equipment must be shaken to be qualified, which is convenient for checking the ground wire left on site.
- Measures to prevent accidental entry into the live interval
In the operation and production of the power station, the operators must ensure that the signs, signs and safety warnings of the equipment, facilities and power distribution sites on the production site should be correct, clear and complete. Inspections and operators should carefully check the name, serial number and location of the equipment, facilities, and places before entering the live equipment site. Identify the specific location of the live equipment by checking the meter parameter indication of the equipment, the sound of the equipment running, etc. to prevent entering the live interval by mistake. Strengthen the safety management of external maintenance personnel. Before the maintenance work starts, in addition to taking good on-site safety measures, a detailed safety disclosure should be carried out according to the actual situation on the site, and the live location and safety precautions should be indicated. - Measures to prevent misoperation in parallel
When the equipment is changed, it is necessary to insist that the transformers, current transformers, and lines are newly put into use (or put into use after overhaul), or the primary circuit is changed, and the wiring is changed. In operation and production, to prevent human misoperation when paralleling, the working factory transformer and the standby factory transformer are not allowed to be directly paralleled when they are connected to power systems with different frequencies. When switching the power supply, the method of “break first, then make” should be adopted. - Prevent personal injury accidents
In order to prevent the occurrence of personal casualty accidents, operators should be at the job site, and should strengthen the analysis of dangerous points on the job site and take various safety measures. At the same time, strengthen the safety skills training of personnel, strengthen the management of tools and equipment in the production work, and improve the safety guarantee level of production operations.
All safety measures at the work or job site must comply with the relevant requirements of the state, the power industry and the power safety work regulations of the public power grid management department. The operation and maintenance personnel should carefully analyze the dangerous points of the job site according to the work content, and take various safety measures accordingly. Hazard analysis efforts should be regularly reviewed to ensure they are relevant and effective. Set up safety warning signs and take reliable protective measures at locations where personal injury accidents may occur on the job site. Complete cross-work safety protection measures should be formulated for cross-work sites.
Photovoltaic operation and maintenance enterprises should regularly train relevant operators on safety regulations, systems, and technologies to make them proficient in relevant safety measures and requirements, clarify their respective safety responsibilities, and improve the ability and level of safety protection. For temporary and new employees, safety technical training must be strengthened, and they must be able to work under the leadership of personnel who have proved that they have the necessary safety skills and have work experience. It is prohibited to assign temporary or new recruits to work alone in hazardous work without supervision. Based on the actual production situation, various forms of safety ideological education should be carried out on a regular basis to improve employees’ awareness of safety protection, master safety protection knowledge and self-rescue and mutual-rescue methods in the event of injury accidents.
Strengthen the management of safety tools. Conscientiously implement various organizational measures and technical measures for safety production, provide sufficient safety tools and protective equipment that have passed the inspection of national or provincial and ministerial quality inspection agencies, and conduct regular inspections in accordance with relevant standards and regulations, and resolutely eliminate unqualified ones. Tools and protective equipment to improve the level of work safety.
- Prevent fire accidents
In the process of safe production, in order to prevent the occurrence of major fire accidents, relevant regulations such as “Typical Fire Protection Regulations for Power Equipment” (DL5027-2015) should be implemented one by one, and the key requirements are as follows:
(1) Strengthen the fire prevention organization and the management of fire protection facilities.
1) Photovoltaic operation and maintenance enterprises should establish an organization to prevent fire accidents. The main person in charge of the enterprise is the first responsible person for fire protection work. It must be equipped with special fire protection personnel and establish an effective fire protection organization network. Improve the firefighting work system and conduct regular inspections on firefighting work. It should be ensured that all internal power stations, teams, and operators understand the key fire protection requirements and fire extinguishing plans within their respective jurisdictions.
2) It is necessary to have complete firefighting facilities, establish a well-trained mass firefighting team, and strive to detect and extinguish the fire in time in the early stage, and make the local fire department understand and grasp the characteristics of fire rescue in the electrical sector so as to put out the fire in time. Fire-fighting facilities should be regularly inspected, expired facilities should be replaced on time, and the use of expired facilities is prohibited.
3) Enterprises should be equipped with necessary positive pressure air respirators in relevant places and conduct necessary training to prevent ambulance personnel from being poisoned or suffocated during firefighting.
4) In the design of new and expanded projects, the fire water system should be separated from the industrial water system to ensure that the fire water volume and water pressure are not affected by other systems, and the backup power supply of the fire pump should be supplied by the security power supply. Fire water systems should be regularly inspected and maintained.
(2) The cable is fireproof.
1) The cable fire protection work must implement the whole process management of design, infrastructure construction and production operation, and take comprehensive measures from all aspects to prevent the cable fire and spread accidents.
2) The selection and laying of cables in new and expanded projects should be designed in accordance with the relevant requirements of the Fire Protection Code for Design of Thermal Power Plants and Substations (GB50229-2019). All cable fire protection measures must be completed in strict accordance with the design requirements, and put into production at the same time as the main project.
3) Strictly follow the correct design atlas, so that the wiring is neat, all kinds of cables are arranged in layers according to the regulations, the bending radius of the cables should meet the requirements, avoid arbitrary crossing and leave enough pedestrian passages.
4) Control room, switch room, computer room, communication room, etc. leading to cable interlayers, tunnels, through floors, walls, cabinets, panels, etc. All cable holes and gaps between the panel surfaces (including cable through wall bushings and cables) The gap between them) must be blocked with qualified non-combustible or flame-retardant materials.
5) When laying cables in the expansion project, close cooperation with the operating unit should be strengthened. The cable holes and damaged fire barriers that penetrate through the equipment of the in-service power station shall be restored and blocked in time.
6) The cable shafts and cable trenches should be divided into sections for fire isolation, and sectioned flame retardant measures should be taken for the cables laid in the tunnels.
7) The number of intermediate connectors of cables should be minimized. If necessary, the cable head should be made and installed according to the process requirements. After passing the quality inspection, it should be sealed with a fire-resistant and explosion-proof box.
8) Establish and improve various rules and regulations such as cable maintenance, inspection, fire prevention, and alarm. Important cable tunnels and interlayers should be equipped with temperature flame and smoke monitoring alarms. Adhere to regular inspections of cable interlayers and trenches, and regularly conduct infrared temperature measurements on cables, especially cable intermediate joints, and carry out preventive tests as required.
9) Cable interlayers, shafts, cable tunnels and cable trenches should be kept clean and free from water accumulation. The lighting should be of safe voltage and sufficient lighting, and it is forbidden to pile up sundries. For hot work in the above-mentioned parts, a hot work ticket should be issued, and reliable fire prevention measures should be taken.
10) Strengthen the fire protection of DC cables. The cables of the DC system should be flame-retardant cables; the cables of the two groups of batteries should be laid separately as much as possible. The maintenance site should have complete fire prevention measures, and the hot work in the fire-proof area (including the cable interlayer) should be carried out according to the hot work management system and hot work ticket work system. During the on-site maintenance of the transformer, there should be a special person on duty, and no one should be on site. The lighting and ventilation equipment in key fireproof and explosion-proof places such as battery room, oil tank room, and oil processing room should be explosion-proof. The unattended substation shall be equipped with automatic fire alarm or automatic fire extinguishing facilities, and its fire alarm signal shall be connected to the monitoring and telemetry system, so as to detect the fire in time.
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