In order to strengthen the supervision and management of the hidden trouble, prevent and reduce the occurrence of the fault, ensure the life of the staff and equipment safety of the power station, the hidden trouble of the equipment is rectified in technical and measures in time, so as to degrade it and predict the accident, so as to prevent the expansion of the fault.
Hidden trouble rectification work is the focus of hidden trouble management, the ultimate purpose of rectification is to eliminate hidden trouble, put an end to accidents. Hidden danger investigation specific to each professional level should also do the following work.
(1) Formulate specific implementation plans according to the way of screening equipment safety hazards.
(2) According to the system equipment, the responsibility shall be implemented to the people, and the hidden dangers of the equipment and the safety measures taken shall be recorded in detail.
(3) the major hidden dangers, or difficult to solve the hidden trouble, to take the necessary temporary security measures in time, and immediately report to the competent department of the temporary security measures must be taken by technology, to ensure safe and reliable in a certain period of time, after the temporary measures should strengthen the equipment inspection, and find new problems and new interim measures, Until the equipment hidden danger is completely rectified.
Photovoltaic power station inspection and pre-test
Pre-test refers to the periodic inspection, test or monitoring of photovoltaic power station equipment in order to find hidden dangers of equipment in operation and prevent accidents or equipment damage, including the test of taking oil samples or gas samples. Pre-test is an important means of fault prevention in photovoltaic power station.
The preventive test cycle length of photovoltaic power station should be selected according to the specific situation of the equipment, and the cycle of important, newly invested and defective equipment should be shortened; The period of insulation stabilization equipment can be extended appropriately. The test site must comply with the “Electric power Safety Work Regulations”, strictly implement the work ticket system, work permit system, work monitoring system, work interruption, transfer and termination system, before the test of the subject, and the bus, transformer, incoming and outgoing cable and other possibly live equipment or devices connected, The electric test and discharge of the tested product must be carried out in strict accordance with the Electric Power Safety Working Procedure.
I. Annual inspection and pre-test of equipment
Annual inspection and pre-test of equipment refers to the regular annual inspection and pre-test of electrical equipment carried out by operation and maintenance personnel to ensure the long-term safe and reliable operation of electrical equipment, timely find and deal with hidden dangers or defects affecting the safe operation of electrical equipment during the working process.
1) The test results should be compared with the previous test results of the equipment, and with the test results of similar equipment, with reference to the relevant test results, according to the law and trend of change, make a comprehensive analysis and judgment.
(2) When the test items, cycles or requirements need to be changed under special circumstances, the main equipment shall be examined and approved by the higher competent department before implementation; the other equipment shall be examined and approved by the chief engineer of the unit before implementation.
(3) Electric equipment below 110kV shall be subjected to voltage resistance test (unless otherwise specified). 110kV and power equipment, when necessary, should be carried out voltage test.
(4) 50Hz AC withstand voltage test, the duration after adding to the test voltage, unless otherwise specified, is Lmin; The test voltage application time for other voltage resistance tests shall be specified in the test requirements for the relevant equipment.
(5) AC voltage test values of electrical equipment with non-standard voltage grades can be calculated by insertion method according to adjacent voltage grades specified in this code.
(6) The oil-filled electric equipment should have enough standing time after oil injection to carry out the pressure test. If the standing time is not specified by the manufacturer, it shall meet the following requirements according to the rated voltage of the equipment:
1) 500 kv > 72 h;
2) 220 and 330kV>48h;
3) 110kV and below >24h.
(7) When carrying out the pressure test, the connected equipment should be separated and tested separately as far as possible (the complete set of equipment assembled by the manufacturer is not in this limit), but the equipment of the same test voltage can be tested together. Several electrical equipment with different test voltages, for which separate tests have been recorded, may also be tested together when it is difficult to perform separate tests, in which case the lowest test voltage in the connected equipment shall be used.
(8) When the rated voltage of power equipment is different from the rated working voltage in actual use, the test voltage should be determined according to the following principles:
1) When the equipment with higher rated voltage is used to strengthen the insulation, the test voltage shall be determined according to the rated voltage of the equipment.
2) When the equipment with higher rated voltage is used as the substitute equipment, the test voltage should be determined according to the rated working voltage actually used.
3) When equipment with a higher voltage level is used to meet the requirements of high altitude areas, the test voltage shall be determined at the installation site according to the rated operating voltage actually used.
(9) When conducting various tests related to temperature and humidity (such as measuring DC resistance, insulation resistance, Tan δ, leakage current, etc.), the temperature of the subject and the temperature and humidity of the surrounding air should be measured at the same time.
When conducting insulation test, the temperature of the subject should not be lower than +5℃, outdoor test should be carried out in good weather, and the air relative humidity is generally not higher than 80%.
(10) In the DC high voltage test, negative polarity wiring should be used.
(11) If there is any change in the national or industrial standard of the product, the implementation shall be adjusted accordingly.
(12) If it is proved by practical assessment that the effect of power outage test can be achieved by using live measurement and online monitoring technology, the power outage test may not be done or the period may be appropriately extended after approval.
Since the pre-test cycle and methods of equipment inspection are different, Table 5-2 is a relatively general periodic table of pre-test items related to the operation and maintenance of photovoltaic power stations.