With the increase of the aging population and the gradual shortage of labor, traditional construction methods are no longer suitable for the needs of the development of the times, while modular and prefabricated models best meet the connotation requirements of construction industrialization. Prefabricated cabin substations have the advantages of few on-site operations, high construction safety, short construction cycle, high land utilization rate, energy saving and environmental protection, etc., and have very broad application prospects.
Performance characteristics of prefabricated cabin substations
- Small floor area. The prefabricated cabin substation adopts a modular design and can be arranged in two layers to save land acquisition costs.
- Website building flexibility. This type of substation does not require high site requirements, and can be arranged flexibly according to the actual conditions of the site (land shape, geology, etc.).
- The amount of construction work on site is reduced. In traditional site construction mode, the amount of on-site civil engineering is large, the equipment is assembled, wired and debugged after transportation to the site, and the construction period is long; in the prefabricated cabin mode, the equipment is prefabricated, installed, wired and debugged in the factory. The site only needs to carry out cabin splicing and cabin indirect lines, which are less affected by the climate and environment, and the construction period is short.
- The complexity of site construction management is reduced. In the traditional model of building a site, the foundation of civil construction is carried out first, then the equipment is installed, and then the power distribution room construction is carried out. The engineering cycle is long, and the management is difficult. In the prefabricated cabin mode, only simple foundation construction of the prefabricated cabin is carried out on site. After completion, the civil construction can be withdrawn, and it is enough to wait for the prefabricated cabin to be in place, avoiding cross-construction, and construction management is relatively simple.
- Good environmental protection. The traditional wet site construction model has a large amount of civil construction and a large amount of dust. It has a large dust pollution to the environment, and has a great impact on the surrounding environment. In the prefabricated cabin mode, the entire cabin is prefabricated to the site, the amount of civil construction on site is small, the impact on the surrounding environment is small, and the environmental protection is good.
- The appearance is exquisite and in harmony with the environment. The prefabricated cabin mode uses customized exterior painting according to the surrounding environment conditions of the booster station, which is in harmony with the environment. At the same time, prefabricated cabin substations have good functions of isolating electromagnetic radiation and silencing noise, and are easily accepted by surrounding residents.
- Short construction period. The construction cycle of the prefabricated cabin substation is short, the foundation construction is synchronized with the production of the prefabricated cabin, and the construction period is about 3 months.
- Low comprehensive cost. The traditional website building model is relatively fixed, and there is limited space for cost optimization. The prefabricated cabin booster station can reduce the cost of civil construction and installation, connect to the grid to generate electricity in advance during the construction period, obtain benefits in advance, and reduce the comprehensive cost by about 10%.
Design technology for prefabricated cabin substations
According to the Q/GDW 1795-2013 “General Rules for 3D Modeling of Power Grids” issued by the State Grid Corporation, 3D modeling design of prefabricated cabin products is carried out using parametric modeling methods and physical modeling methods.
(1) Parametric modeling. A modeling process that uses multiple sets of parameters to constrain the relationships and dimensions between geometric elements of a graphic, drives the generation of geometric shapes with different topological relationships, and modifies and controls the geometric shape of the graphic by adjusting the parameters, can quickly realize three-dimensional modeling of similar prefabricated cabin products.
(2) Solid modeling. The parametric model is used as a reference for physical modeling, and the parameters of each 3D voxel are associated with it. After refining the components of the prefabricated cabin (roof, wall, base and integrated equipment), it is assembled into a three-dimensional model of the prefabricated cabin product.
(3) Production drawings. Production drawings of various parts are generated using physical modeling, and a list of materials for related materials is automatically generated. At the same time, it is possible to scan the QR code of the drawing and preview the 3D model online, so as to improve processing and production efficiency.
(4) Visual rendering. Advanced visual rendering technology is applied to render the details of elements such as the exterior, interior scenes, and ambient lighting of the created prefabricated cabin model, to realize the digital visual design of the prefabricated cabin, and show users the full range of product forms.
CAE simulation technology is used to simulate working conditions such as hoisting, wind load, snow load, earthquake, etc. for the designed prefabricated cabin structure to verify the reliability of the cabin structure, and achieve the purpose of reducing design costs, shortening the design cycle, and improving product reliability.
(1) Simulation of hoisting conditions. CAE simulation technology was used to analyze the stress deformation under gravity load during lifting of the prefabricated cabin module. The lifting point is located on the 4 lug mounting holes on the bottom channel steel of the single module.
(2) Simulation of snow-carrying conditions. Using CAE simulation technology, according to the requirements of GB50009-2012 “Building Structure Load Specification”, the structural stress condition of the prefabricated cabin was simulated under snow load conditions during the 50a reproduction period.
(3) Wind load operation simulation. Using CAE simulation technology, according to the requirements of GB50009-2012 “Building Structure Load Specification”, the structural stress condition of the prefabricated cabin was simulated under wind load conditions on various surfaces of the double slope roof building.
(4) Modal decomposition. Unlike the self-vibration cycle characteristics of high-rise building structures, the prefabricated cabin structure is formed by welding a large number of steel profiles, and its natural frequency should be calculated according to the modal decomposition method. The obtained modal and fortified seismic spectra can be used to analyze the response of the prefabricated cabin seismic spectrum.
(5) Seismic conditions simulation. Using spectral response analysis technology, the structural stress condition of the prefabricated cabin under the condition of 8 degrees seismic fortification intensity level was simulated according to the requirements of GB50260-2013 “Seismic Design Specification for Electric Power Facilities”.
(6) Illuminance simulation. Illuminance simulation software is used to simulate and calculate the illuminance values for normal lighting, accident lighting and emergency evacuation lighting in prefabricated cabins to meet the illuminance requirements in the DL/T5390-2014 “Technical Regulations on Lighting Design for Power Plants and Substations” to ensure a comfortable operating and maintenance environment inside the cabin.
Process technology for prefabricated cabin substations
(1) Production process. The prefabricated cabin substation uses factory standard processing, which can guarantee the product quality of the prefabricated cabin.
(2) Anti-corrosion process. According to different application scenarios, substations select different anticorrosive grades and spray processes to ensure stainless corrosion during the life cycle of prefabricated cabins.
(3) Insulation process. The prefabricated cabin substation uses a three-layer insulation cabin structure of “steel plate+rock wool & polyurethane+computer room wall panel & marine fireproof insulation rock wool board”, which is complemented by a heater and air conditioner to ensure that the temperature inside the cabin is within an appropriate range.
(4) Waterproofing process. For compartmentalized cabins that are prone to water leakage, compression ratio sealant and weather resistant silicone sealant are used to seal them, and combined with a waterproof cover to ensure that the cabin does not leak water.
(5) Dustproof process. The prefabricated cabin substation uses a sedan sealing process, that is, a highly elastic sealing strip (EPDM rubber), which is dustproof, moisture-proof, and anti-condensation. The high-voltage and low-voltage inlet and outlet cable holes use knockdown holes that are easy to seal, and sealant rings for knockdown holes are randomly arranged in the cabin.
(6) Ventilation process. In consideration of climatic conditions and environmental factors, electric air valves or micro positive pressure dustproof technology are used in the prefabricated cabin for windy sand areas, extremely cold regions, and high sewage areas to achieve dustproof, moisture-proof and anti-condensation effects, and ensure the stable operation of the equipment.
(7) Interior craftsmanship. Pipeline distribution lighting uses flame-retardant PVC threading pipes, fire protection and access control equipment are embedded with galvanized pipes; secondary floor equipment generally uses anti-static floors, primary equipment generally uses insulating rubber pads; ceilings use skeletal integrated ceilings, which are easy to install, beautiful overall, and convenient for later maintenance.
(8) Power distribution process. The prefabricated cabin is equipped with a power distribution box, a normal lighting distribution box, an emergency lighting distribution box and a maintenance box according to the requirements of each function. Among them, the emergency lighting distribution box can provide 36V centralized power supply, which can realize functions such as remote monitoring and fire fighting linkage.
Conclusion
Modular prefabricated cabin substations will gradually be recognized by builders and engineers for their many advantages such as factory-ready production, saving construction time, good sound insulation and shielding effects, high safety and reliability, and low construction and operation costs. It is believed that in the construction process of future urban center substations, industrial park user substations and new energy grid-connected substations, modular prefabricated cabin substations will surely be more widely used.
