Talking about the operation and maintenance of pho

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Talking about the operation and maintenance of photovoltaic power stations

as an important asset, the importance of operation and maintenance of photovoltaic power stations is self-evident. From the perspective of operation and maintenance, for power stations built and held by enterprises themselves, or outsourced to a third party but held by themselves, in the whole process of construction, from the early project development, system design, construction and completion acceptance, operation and maintenance personnel are required to control, Including some preliminary data, technical data (including equipment data, acceptance documents, contracts and financial documents) involved in the handover of the power station from the general contractor to the owner. In addition, for the purchased power station, the above required documents, relevant procedures and contracts must be complete. At the same time, the overall quality of the power station also needs to be tested and evaluated, and the work that needs to be rectified should also be completed before handover. However, looking at the reality, the operation and maintenance of the power station will face various difficulties, such as the poor cooperation of the construction party, the delay in problem rectification, the uneven quality of the power station, the poor quality of inefficient components, many unreasonable system designs, serious construction quality and so on, which have been lingering in the minds of the operation and maintenance personnel. These problems need our attention

for the power station that has been taken over, first of all, it is necessary to formulate a reasonable division of operation and maintenance and scientific management system according to its own power station and staffing, such as production and operation system, safety management system, emergency fire protection system, equipment operation regulations, etc., of which the daily inspection work with a record high output stipulated by the production and operation system, regular inspection and inspection under special circumstances are essential, It can grasp the operation status of the power station in time, find existing or potential problems, and ensure normal power generation. Safety management runs through the whole process of operation and maintenance, including the rational use of safety tools and instruments and safe operation specifications, so as to ensure personal safety and equipment safety. Due to the limited on-site operation skills and fault diagnosis and analysis experience of novices, skilled personnel are required to train them. For the high-voltage electrical part, it is also necessary to have a high-voltage operation permit before taking the post

during the operation of photovoltaic power station, faults will occur on both DC side and AC side. Although the frequency of faults is less for inverter, booster station and collecting cable, once faults occur, it will have a great impact on power generation. The faults can be seen from the real-time operation status of background monitoring. As for the square array strings on the DC side, due to the large number of strings, the faults are not easy to be found, and the frequency of faults is high, which has an important impact on the power generation. At the same time, there is also some room for improving the power generation in this part, which needs the attention of the operation and maintenance personnel. Figure 1 shows the statistical curve of fault frequency and proportion of each equipment on the power station. It can be seen from the figure that the total fault frequency of components, combiner boxes and inverters accounts for about 90% of the total fault proportion, while the faults of cables, box transformers, civil engineering and booster stations account for a relatively small proportion. Component problems such as component looseness, hot spot failure, glass rupture, junction box diode failure, etc. these problems are mainly related to their own quality, except that the components are loose due to the non fastening of the pressure block during construction

Figure 1 Classification of power station problems

combiner box mainly focuses on fuse burnout (fuse quality or the rated current of the selected fuse is too small), circuit breaker problems (such as heating and tripping), abnormal communication (including damage to the communication acquisition module of the combiner box), terminal heating (loose terminals, excessive resistance), branch fault (grounding fault, overcurrent), DC arcing and other problems. Refer to figure 2

Figure 2 common faults of combiner box

inverter mainly focuses on module (main board) fault (generally caused by poor exhaust system and excessive cabinet temperature), module over temperature (module heat dissipation problem), fan damage, fuse burnout, smoke sensor fault, circuit breaker trip, abnormal startup, grounding fault, etc. DC cables are mainly concentrated in grounding fault, insulation skin damage (caused by construction or vehicle rolling), cable head breakdown, cable heating (the design of the design institute is inconsistent with the actual situation, and the wire diameter is small, so heating will be difficult to avoid), short circuit, etc. for example, the skin is damaged during construction, and the buried depth is shallow, especially some ground power stations have sandy gravel soil. If the cable buried depth is shallow, the operation and maintenance vehicles are out of date by providing full-automatic power failure protection, It is easy to crush the cable and cause damage, which requires the O & M to find and deal with it in time during patrol inspection. Other problems include the foundation subsidence of the power station, or the support inclination caused by the collapse of the land due to rainwater scouring, and some have not been provided with flood control measures. The outdoor oil tank transformer mainly has oil leakage, low oil level, circuit breaker failure and other problems

during the operation of the power station, the above common faults may occur again in the future operation, or new problems may be exposed. What we need to do is to analyze and classify the faults regularly through the above similar methods, deal with them as soon as possible after the faults occur, strengthen the patrol inspection of the fault prone areas, and try to minimize the fault loss. On the other hand, fault discovery, analysis For the operation and maintenance personnel, the solution process is also one of the ways to improve their ability

with the increasing scale of photovoltaic power stations owned by enterprises, the traditional power station management methods are not applicable. Under this background, the power station operation and maintenance system tailored for power station operation and maintenance came into being. It not only reduces the workload of operation and maintenance personnel, which requires operators to manually switch controllers, but also has very powerful functions, such as data collection Data analysis (meteorological data, power generation statistics, PR analysis, equipment operation), string fault location, alarm center, defect management, automatic report management and other functions. Among them, the data is the key to the operation and maintenance system, such as the current and voltage data of combiner box string, the real-time voltage, power generation, real-time power and other data of inverter, as well as the real-time data of box transformer, high voltage in the middle side of the reporting link, parallel point and other key points. The operation and maintenance system is based on real-time data, which makes the operation and maintenance of the power station more efficient. It is a very effective technical means. However, the daily inspection work still needs to be continued, because some problems are blind spots for the operation and maintenance system, which are difficult to find. For example, there is no effective real-time monitoring means for the temperature of the equipment terminal. If the temperature continues to be high, it will bring potential safety hazards. The operation and maintenance personnel generally scan the equipment terminals in the photovoltaic area and the booster station through the infrared thermal imager to find the temperature abnormal points, Eliminate hidden dangers in the bud

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