With the steady and sound development of economy, science and technology have also achieved rapid development and progress. At the same time, the speed of energy consumption also presents a momentum of rapid growth, which also promotes the construction and technical level of grid-connected photovoltaic power stations to achieve continuous rapid improvement. With the rapid growth of installed capacity, grid-connected photovoltaic power station construction, installation and commissioning work is particularly important. In view of this, this paper analyzes and discusses the key points of civil construction, installation and commissioning of grid-connected photovoltaic power station. In recent years, with the gradual implementation of the concept of sustainable development, China has paid more attention to the rational utilization of renewable resources, which has indirectly promoted the construction and development of grid-connected photovoltaic power stations. The total installed capacity in China also shows a rapid growth trend within a short period of time. Combined with the current construction of grid-connected photovoltaic power station, based on the technology and management level, in-depth analysis and research on the key points of grid-connected photovoltaic power station civil construction and installation and commissioning projects has a very key influence and practical significance for the development and construction of grid-connected photovoltaic power station.
Ⅰ. Analysis of key points of civil engineering
As for grid-connected photovoltaic power stations, the main points of civil engineering construction usually cover the following aspects: First, a unified standard scientific management system should be established in the temporary construction and on the wall, and the “six cards and one picture” should be hung on the wall in an appropriate location in all projects; Second, the construction site of the road, because the grid-connected photovoltaic power station construction area is relatively wide, therefore, the site store a large number of support components, before the formal start of construction, should take scientific and systematic planning of the road, safety warning, drainage facilities, etc., to ensure the safety and smooth site road; Third, regarding the transportation and storage of equipment, comprehensive and overall analysis should be made. Materials and equipment should be placed in the specified area, and a reasonable distance should be kept from the site as far as possible to ensure the smooth road of the transportation site. At the same time, the material stacking area should be well ventilated and drained, clean and tidy, and take safety measures such as rain prevention and theft prevention to avoid material loss caused by mismanagement; Fourth, during the construction of civil support, it will involve bored pile, strip foundation, independent foundation and many other construction links. It requires all construction units (general contractors) to be sure to carefully understand the content of each link of the design document, and formulate a scientific and feasible construction plan according to the specific situation of the construction site; Design drawings for strict construction make precise control of pay-off, carry out excavation construction according to pay-off, and ensure that all parameters can fully meet the strict construction standards. Take cast-in-place pile as an example to illustrate its construction process: Site leveling → Preparation before spud (measuring lofting, drilling machine and other equipment in place) → drilling → clearing → steel bar making and installation → placement of embedded parts → concrete pouring → concrete curing; Fifth, about the inverter construction, according to the requirements of the design drawings, clear the inverter setting position, to ensure that the inverter is not easy to be destroyed after installation; Sixth, regarding the foundation construction of the box transformer, the pay-off construction shall be completed according to the drawing design, to ensure that the pay-off size and position are accurate, and the depth shall also meet the strict construction standards; Seventh, regarding the construction of the internal fence, it should be strictly based on the construction process. The first step is to start the laying out measurement, and then finish the mold making and processing, size determination, concrete casting, mold removal, and finally the fence installation.
Ⅱ. Analysis of key points of installation and commissioning engineering
1. Install the support
Before the formal start of installation, should take a comprehensive system of careful inspection, inspection content is about to ensure that there are no defects and quality problems on the surface of the support, remove the support surface burr or welding waste slag, and again complete the size measurement work, to ensure that the installation point position and support size can maintain a perfect match with the construction foundation. During the installation, the support should be effectively connected to the foundation in the form of embedment. After the connection is completed, the support should be effectively reinforced in the form of bolt connection. During connection, ensure that the main bolt is accurate.
2. Install photovoltaic modules
The transportation and storage of components shall be in accordance with the manufacturer’s specific regulations. Before unpacking components, the manufacturer, supervisor and owner must be informed to go to the site for unpacking inspection, check the size, brand, certificate, technical parameters and appearance of components against the contract, design and supply list, and organize the record of unpacking inspection, and use after the inspection is qualified. The installation of support shall pass quality acceptance before assembly installation. The models and specifications of the components shall meet the design requirements. The appearance and components of the components must be intact. Installation personnel must be trained in related installation knowledge and provided with technical information. The installation of the modules shall comply with the regulations, and the installation of the photovoltaic modules shall be carried out according to the design drawings. The torque value of the component retaining bolt shall conform to manufacturer’s or design document. Component installation and construction contents: (1) Fixed installation of bracket and solar module; (2) Serial connection of solar cells; (3) Connection of solar cell connection line and DC confluence box; (4) Electrical detection of group string connection performance; The above operation process shall be carried out in sequence and shall not span the construction.
3. Install the busbar
During the installation and commissioning phase of grid-connected photovoltaic power station, the key role of the junction box is to parallel several groups of series loops and connect them to the interior of the junction box, so as to ensure that the direct output DC current can be larger and stronger, and then directly with the inverter, through the inverter to DC into AC current. Therefore, during the installation of the bushing box, it is important to consider the parallel distance of the loop to avoid large distance, so that the electric loss can be effectively reduced.
4. Install the inverter
As for the inverter, its key role is power conversion, therefore, before the installation, be sure to carefully check the quality of the equipment and components, the specifications and standard parameters, etc., should fully meet the strict regulations of design and construction, before installation and use. During the installation, the construction special transportation equipment to be reasonable use, located in the inverter room door to build a reversal platform. Through the collocation of lifting equipment, the inverter is installed to the bearing channel steel foundation. Then, based on the strict standards of construction design, the inverter is firmly fixed with appropriate methods. During the fixed period, full attention should be paid to the fixing of the inverter and the channel steel foundation, and the earthing setting of the channel steel foundation should also be ensured. During the DC side connection of the inverter, ensure that the busbar switch is kept in the state, and scientifically test the safety and reliability of the installation environment based on the insulation test. After the end connection is completed, fire blocking should be used to avoid unnecessary safety problems.
5. Install the container
Before installation, strictly check the variable parameters of the box to check whether they are in conformity with engineering standards, and check whether the equipment and construction are damaged or have defects. Based on engineering standards, careful planning of material storage, accurate identification of material characteristics, and waterproofing. After the completion of the construction of box transformer foundation and channel steel, the construction site shall meet the specific construction standards for the installation of box transformer, and through the use of lifting equipment, the box transformer shall be hoisted to the designated area and dropped to the channel steel foundation, and the reliable fixation between the box transformer and channel steel foundation shall be completed by reinforcement method. After installation, should be located on the surface of the box for complete and accurate representation. At the same time, in order to ensure installability, it is necessary to conduct scientifically rigorous insulation tests before terminating.
6. Cable trench and cable (and communication optical fiber) laying
The depth and distance of cable trench excavation should be accurately controlled to meet the specific standards related to cable trench construction design. At the same time, it should be ensured that different types of cables of high voltage and communication should be laid separately. The distance between cables should also be strictly controlled, usually at about 0.5m. After the cable laying is complete, the sand laying should be completed. The sand laying should be uniform, the brick laying should be reasonably designed, and the distance should be accurately controlled.
7. Perform grounding
During the grounding construction, the excavation depth shall be consistent with the construction design standard, and the grounding excavation construction shall be synchronized with the cable laying as far as possible, so that one trench can be used for both purposes. In addition, based on the construction design requirements, complete the flat iron welding construction and grounding pole. The width of the welding surface should be controlled to be twice that of the flat iron, and the distance between the butt poles should be strictly and accurately controlled. After the grounding pole is made, the support, box transformer and inverter and the distribution room shall be grounded in turn. After the grounding is finished, the grounding effect shall be strictly tested, and the resistance test method shall be used to test whether the construction can meet the strict standards.
8. Debugging and grid connection
Firstly, inverter debugging. As the key core equipment of the power station, the key role of inverter is to complete the current conversion, so that the DC current deficit can be changed into AC current. Therefore, before debugging, it is necessary to carefully check the specific wiring condition of the DC side and AC side of the inverter, and effectively check the correctness and stability of the wiring position. The scientific measurement of current and voltage is completed through the measuring equipment, and the normal output of photovoltaic modules can be ensured only when the results are free from abnormal conditions. Second, scientific tests should be carried out on cables. The test procedures are as follows: (1) nuclear phase and insulation monitoring of low-voltage cables; (2) high-voltage cable withstand voltage monitoring; (3) direct resistance test and nuclear phase; (4) cable connection test. Third, it is necessary to adopt the box change test, the test process is as follows: (1) brand-name parameters; (2) transformer rolling test; (3) insulation and DC resistance monitoring; (4) partial discharge monitoring; (5) Group, core insulation test. Fourth, it is necessary to adopt the equipment debugging of the booster station. The debugging process is as follows: (1) one time equipment debugging; (2) secondary equipment debugging; (3) four-remote signal debugging.
Ⅲ. Construction quality control key points analysis
First of all, during the construction period, careful and strict comprehensive inspection should be carried out on the construction site area and each construction link, and the three-level detection system should be fully and effectively implemented. First, the construction unit should carry out self-inspection to detect whether there are illegal behaviors and quality problems during the construction period. If problems are found, scientific and reasonable proper treatment should be made in time; Second, the supervision unit is responsible for carrying out special inspection, especially to carry out strict and careful inspection of hidden works and details, and to carry out strict quality control of key construction nodes and key construction points; Third, the construction unit arranges experts to go deep into the construction site area, fully understand the specific situation, make strict inspection of the construction and the specific implementation of the construction design drawings, and take a comprehensive and strict inspection of the construction site area. Secondly, strengthen construction material quality and construction behavior control. The detection of construction materials has also become the key to control the construction quality from the source. Construction behavior detection is to prevent the adverse impact of human factors on the construction quality. Scientific and strict quality management for the two aspects can lay an important foundation for the construction quality.
Ⅳ. Conclusion
To sum up, with the development and construction of the power industry, grid-connected photovoltaic power station construction has become an important development trend. In the construction stage of photovoltaic grid-connected power station, it is especially necessary to pay special attention to the civil construction and installation and commissioning engineering, and to conduct key analysis and research, so as to provide reliable guarantee for the civil construction and installation and commissioning engineering, ensure the overall quality and smooth development of photovoltaic power station construction, and promote the stable and sound development of the power industry.
