Photovoltaic power station safety production management

Two-vote three-system-the specification and implementation of two-vote

Two-vote three-system-the specification and implementation of two-vote

Case 1: On June 8, 2019, a photovoltaic power station applied for the interval power outage and soot blowing cleaning work of the photovoltaic collector I feeder, and received the dispatch permission, and then received the dispatch order to change the collector I line from operation to maintenance. Zhang Mou, an on-duty employee, was an old employee. Because of frequent operations, he did not fill in the operation ticket, and went to the scene to operate with Dong Mou who was on duty at the same time. Because it was summer and the weather was hot, Zhang did not wear protective equipment after arriving at the scene, and started to operate directly, while the guardian Dong Mou was at a critical moment playing mobile games, so he told Zhang: “You are an old employee, this kind of thing. You can do the normal operations alone!”.

Zhang suddenly got stuck while shaking the car, and immediately asked Dong what to do next. Dong Mou told Zhang Mou based on his own experience: “This phenomenon should be a mechanical failure, and the guide rail may not be operated for a long time, so don’t worry, just shake it out vigorously.” Without thinking about it, Zhang shook out the trolley with all his might. When he opened the front door, he found that the air plug of the circuit breaker was stuck, causing mechanical damage to the equipment and loss of productivity of the power station.

Analyzing Case 1, the following problems can be found:
(1) Zhang did not fill in the operation ticket during the operation and carried out illegal operations.
(2) The guardian neglects his duties and commands illegally.
(3) The operator did not wear protective equipment correctly and operated illegally during the operation.
(4) The guardians and operators did not correctly implement the “two votes and three systems”, which led to the occurrence of the accident.

(1) Overview of “two votes”

The function of the work ticket is mainly to stipulate the organizational measures, technical measures and related work procedures and work requirements that must be followed for on-site operations, and serve as a textual basis for guiding safe on-site operations. The operation ticket is the written basis for the electrical switching operation.

“Two votes” is an important measure to ensure the safety of people and equipment in the power system. “Work with tickets, operate with tickets” and effectively reduce the probability of misoperation, so as to achieve the purpose of ensuring the safety of people and equipment. When operating electrical equipment, it is necessary to strictly follow the “two votes” requirements, keep in mind the “three nos, four strict” requirements, achieve “four clear, four in place”, and prevent work without tickets and illegal operations.

The specific requirements of “three nos and four strictness” are: do not go to wrong intervals, do not expand the scope of work at will, do not unlock without authorization; strictly follow the work ticket and operation ticket system, strictly follow the work ticket and operation ticket system, strictly implement the work permit system and Work guardianship system, strictly implement the work interruption, transfer and termination system.

The specific requirements of “four clear and four in place” include: firstly, on-site operation guarantee tasks are clear, dangerous points are clear, operation procedures are clear, and preventive measures are clear; second, personnel are in place, measures are in place, implementation is in place, and supervision is in place.

In case 1, the operator did not follow the “two-vote three-system” operation, worked without a ticket, and operated in violation of regulations, resulting in production accidents and losses to the enterprise. In the production and operation of photovoltaic power plants, similar cases like Zhang and Dong are not uncommon. In the operation of electric power production, enterprises need to strengthen personnel safety training and implement the requirements of “work by ticket and operation by ticket” in power safety production; in the implementation of “two tickets”, the issuer, person in charge, The “three kinds of people” of the licensor” carry out safe production operations. Eliminate safety production accidents such as illegal operations and illegal command causing personal and equipment injuries.

(2) Requirements for filling out and executing “two votes”

  1. Work ticket

The work ticket refers to that in the equipment inspection (maintenance), installation, test and other work of power production, in order to ensure the reliable isolation of the work scope and the operating equipment, and to ensure the personal safety and equipment safety during the work process, the operator and the operator are clearly identified. Safety responsibility, written safety agreement signed by both parties.

According to the different scope of application, the work ticket is divided into the first type of work ticket and the second type of work ticket. The first type of work ticket is suitable for those who work on high-voltage electrical equipment and lines, work on secondary wiring and lighting circuits in high-voltage rooms, need to power off high-voltage equipment or take safety measures, and work on high-voltage motors and towed machinery. Workers on the device. The scope of application of the second work ticket: low-voltage live work and work on the shell of live equipment (including lines); work on control cabinets, low-voltage power distribution cabinets, power distribution boxes, and power mains; Equipment power failure or installation of barriers; work on the excitation circuit of a running generator or the rotor circuit of a high-voltage motor; off-duty personnel use insulating rods and voltage transformers for phasing or use a clamp-type ammeter to measure the current of the high-voltage circuit, etc.

(1) Filling in the work ticket and requirements.
1) The job ticket generated or printed by computer should use a unified ticket format, be verified by the job issuer and be executed manually or electronically.
2) For the work ticket generated by computer, each unit should formulate corresponding management system and strictly implement it.
3) The work ticket filled in by hand should be filled in and signed with a pen or ballpoint pen, in duplicate, the content is correct, filled out clearly, and no alterations are allowed. If there are individual mistakes or missing words that need to be revised, the standard symbols should be used, and the handwriting should be clear.
4) In a work ticket, the work issuer, the person in charge of the work, and the work permit person shall not be concurrently appointed. The person in charge of the work can fill in the work ticket.

(2) The use of work tickets.
A work leader cannot execute multiple work tickets at the same time, and the work place listed on the work ticket is limited to one electrical connection part.

(3) Service and permit requirements for work tickets.
1) The first type of work ticket should be delivered to the operating personnel in advance one day before the work, which can be delivered directly or transmitted by fax or local area network. The single-fax work ticket permit should be performed after the official work ticket arrives. Temporary work can be handed over to the work permitter directly before the start of work; the second type of work ticket, the work ticket for live work can be sent before the start of work on the day.

2) After receiving the work, the substation operators should carefully check whether the safety measures filled in the work ticket are correct, perfect and in line with the site conditions according to the work tasks and the actual operation of the field equipment. If not, they should return to the person in charge of the work , the work ticket will not be accepted.

3) After the operator has passed the review, according to the switch or isolation switch that should be opened in the safety measures of the work ticket, the ground wire should be installed, the ground isolation switch should be closed, etc. After verification with the actual on-site measures, the corresponding Put a check mark in the executed column, and fill in the corresponding content in the column of “Supplementary Workplace Retention of Live Parts and Safety Measures”. After checking, the work permit formalities can be processed.

4) Work permit system After the work permit person completes the safety measures at the work site, he should also complete the following procedures before the work shift can start work: ① Go to the site together with the person in charge of the work to re-check the safety measures taken, and specify the specific equipment. The actual isolation measures prove that the maintenance equipment is indeed free of voltage. ② The person in charge of the work indicates the location of the live equipment and the matters to be paid attention to during the work. ③ The person in charge of the work shall confirm and sign the work ticket respectively. ④ The work permit person shall fill in the permit start time. Before the permit procedures are completed, the staff and vehicles shall not enter the work site (equipment area).

(4) End of work and end of work ticket.
1) After all the work is completed, the work class should clean and organize the site. The person in charge of the work should make a thorough inspection first, and after all the staff have evacuated the work place, explain the work items, the problems found, the experimental results and the existing problems to the operating personnel, and check the equipment status and status together with the operating personnel. There are no leftovers, whether it is clean, etc., and then sign the work end time on the work ticket. After both parties sign, it means the end of the work.

2) The work ticket cannot be terminated until the temporary barrier on the work ticket has been removed, the sign has been removed, the permanent barrier has been restored, the grounding wire has not been opened, and the grounding isolation switch has been reported to the dispatcher.
3) After the work ticket is executed, the “Executed” chapter will be stamped.

  1. Operation ticket

The operation ticket is the written basis for the electrical operation of the power system, and it is the main measure to prevent misoperation, including mis-pulling, mis-closing, mis-pulling or closing the isolating switch, mis-taking the ground wire and closing. The types of operation tickets include single operation tickets and gate operation tickets. Switching operation of electrical equipment Electrical equipment is divided into three states: running, standby (hot standby and cold standby), and maintenance. The operation process of electrical equipment from one state to another state is called switching operation.

(1) The method used for the switching operation.
1) Guardian operation: two people perform the same operation, one person monitors and one person operates. During the operation, the guardian and the operator keep an arm-length distance.
2) Single-person operation: The operation is completed by one person; the equipment, projects and operation personnel for single-person operation shall be approved by the equipment operation management unit, and the personnel shall pass the special assessment.
3) Operation by maintenance personnel: operations completed by maintenance personnel. The maintenance personnel of the company who have passed the examination and have been approved by the equipment operation management unit can carry out the monitoring operation of electrical equipment from hot standby to maintenance or from maintenance to hot standby. The guardian should be the maintenance personnel or equipment operation personnel of the same unit. The procedures for receiving and issuing orders and safety requirements by the maintenance personnel shall be reviewed and approved by the technical person in charge of the equipment operation management unit, and reported to the relevant departments and dispatching agencies for the record.

(2) Requirements for filling out the operation ticket.
1) The operator shall fill in the operation ticket for the switching operation.
2) The operation ticket should be filled out item by item with a pen or ballpoint pen. The operation ticket issued by the computer should be consistent with the handwritten format; the ticket surface should be clear and clean, without alteration, and it is strictly forbidden to reverse the order of operations such as adding items and adding items. The operator’s guardian shall check the filled operation items according to the simulation diagram or wiring diagram, and sign respectively, and then run the person in charge of the duty to review the signature.
3) Each operation ticket can only fill in one operation task. The operation task should use the double name of the equipment and comply with the normative terms stipulated in the scheduling regulations. The operation item can only write the equipment number.

(3) Normative requirements for switching off operation.
1) The switching operation must be carried out according to the instructions of the duty dispatcher or the person in charge of the running duty.
2) There must be an operation ticket for the switching operation. Each operation ticket can only fill in one operation task. No ticket operation and abandonment operation are not allowed.
3) Do not change the operation ticket without authorization during the operation, and do not release the lock at will.
4) Before starting the operation, check the simulation rehearsal on the simulation diagram (or the computer monitoring device) for correctness, and then carry out the operation.
5) There must be two people for the switching operation, and the operation monitoring system should be strictly implemented. Generally, the personnel who are familiar with the equipment should be supervised and operated by the on-duty personnel.

(4) Precautions for switching off operation.
1) In addition to accident handling, the switching operation should be avoided as much as possible during shift change and heavy load. In thunderstorm weather, it is strictly forbidden to switch off.
2) Before the bus is charged, the voltage transformer should be added to the operation.
3) The following operations can be performed by using the isolating switch: ① Pull and close the voltage transformer and arrester without fault. ② Pull and close the busbar and the capacitive current of the equipment directly connected to the busbar. ③ No-load transformers whose pulling and combined excitation currents do not exceed 2A and no-load lines whose capacitor currents do not exceed 5A.
4) When manually pulling and closing the isolating switch, it must be done quickly and decisively. After the isolation switch is operated, it should be checked whether the operation is in place.
5) When in doubt about the scheduling instruction, you should ask clearly before operating; when scheduling repeated instructions, you must execute it. If the operation instruction directly threatens personal and equipment safety, it can refuse to execute and report to the power grid dispatching department and the supervisor of the unit.
6) When performing an operation task, no substitutions are allowed in the middle, and it is strictly forbidden to do anything unrelated to the operation during the operation.
7) Safety helmets and insulating gloves must be worn during operation. When operating outdoor high-voltage equipment in rainy days, the insulating rod should have a rain cover and insulating boots should be worn. When the grounding resistance does not meet the requirements, insulating boots should also be worn for operation on sunny days.
8) It is strictly forbidden to release the locking operation during the operation. If the operation must be unlocked, it should be reported to the superior leader for approval before proceeding.

Case 2 The process of switching off operation to operation and maintenance (a photovoltaic power station in Guangwei, Hebei, see Figure 1)
(1) The first step: five-proof machine simulation operation.
1) According to the completed operation ticket for the reverse gate, conduct a simulated rehearsal on the five-proof machine, confirm that the operation ticket is correct, and then download the operation ticket.
2) Operators, repeaters and guardians must check and confirm the operation ticket; finally report it to the person in charge of the shift for approval.

(2) Step 2: Disconnect the 321 switch of PV 1 line as soon as the monitoring host operates remotely.
1) According to the requirements of the five defenses, the main wiring diagram screen is not allowed to operate, and must enter the interval sub-diagram to operate.
2) The operation interval should be confirmed during operation, and the switch interval number and operation password should be input after correct.
3) After the operation is completed, it is necessary to go to the site to confirm the switch status and check whether there is any abnormality.

Figure 1 - Turning off operation - operation and maintenance process
Figure 1 – Turning off operation – operation and maintenance process

(3) Step 3: Pull the trolley of the photovoltaic first-line 321 switch to the test position.
1) The switch-off operation must be carried out by two people, and the operation monitoring system must be strictly implemented.
2) Strictly follow the steps shown in the five-proof key to unlock, and confirm whether the operation interval is correct before operation.
3) Confirm that the circuit breaker is in the separation position; during the operation, the operator should maintain a stable posture and shake the trolley out of the working position at a constant speed.
4) After the operation is completed, check whether the mechanism is in place and whether the display position of the operating display device is correct.
5) Before operation, check whether the safety tools are in good condition and wear them correctly.

(4) Step 4: On-site operation, turn on the grounding isolating switch 321-27 of PV 1 line.
1) The switch-off operation must be carried out by two people, and the operation monitoring system must be strictly implemented.
2) Strictly follow the steps shown in the five-proof key to unlock, and confirm whether the operation interval is correct before operation.
3) Press down the cover of the operation hole of the grounding switch, confirm the closing direction and operate it.
4) After the operation, check the position of the grounding isolating switch.

Read more: What is a main transformer?

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