Offshore wind cables and technical difficulties
Due to the harsh and unpredictable nature of the seabed environment, submarine cables for offshore wind power are cable varieties that are difficult to design and manufacture. Submarine cables not only require special features such as waterproof, corrosion resistance, resistance to mechanical pull and external impact, but also require high electrical insulation performance and high safety and reliability, especially for large-length submarine cables and submarine photoelectric composite cables. At present, the manufacturing capacity and technical level of the cable industry pose great challenges. The submarine photoelectric composite cable is a fiber unit with optical communication function and a reinforced structure added to the submarine power cable, which has dual functions of power transmission and optical fiber information transmission, and can completely replace the submarine cable and submarine optical cable laid on the same line. Marine routing resources, lower manufacturing cost, offshore construction costs, and land-and-street landing fees directly reduce the overall cost and investment of the project, and indirectly save the workload of the marine survey and the subsequent maintenance of the route. Submarine cable waterproof When mechanical damage or external force causes damage to the cable jacket and insulation, and the joint is damaged, moisture or moisture will saturate along the longitudinal and radial gaps of the cable, reducing the electrical strength of the insulation. Therefore, most high-voltage submarine cables have a longitudinal direction that prevents moisture intrusion. Radial waterproof measures. The radial measure is mainly to wrap the semiconductive resistance water expansion band outside the insulation shielding and the metal shielding layer, and to add a metal waterproof layer or a metal sheath outside the metal shielding layer. The medium voltage cable has a relatively low electric field intensity, generally aluminum-plastic composite is used. Sheaths, there are also only polymer sheathed, high-voltage cables use lead, aluminum, stainless steel metal sealing sleeve. The polymer sheath is water-repellent, but it has a certain water absorption. This is because the structure is mainly a semi-crystalline polymer composed of a crystalline phase and an amorphous phase. The crystal phase has a compact structure, the molecules in the amorphous phase are loose, and there are large gaps between the molecules. Under the action of the alternating electric field, the polar water molecules constantly flip back and forth, and can penetrate into the insulating material through gaps and grain boundary defects. When the polymer sheath is used, a water blocking agent with water absorption is added in the sheath. Offshore wind cables and technical difficulties Offshore wind cable XLPE submarine cable Electrical performance and mechanical performance are also better than oil-filled cables. The development of XLPE insulated submarine cables has a broader perspective, but there are still many technical issues that need to be resolved. Ordinary cross-linked polyethylene cables under the action of a direct voltage, the space charge in the cable insulation will be concentrated somewhere, resulting in the breakdown of the local field strength is too high here. The use of additives in insulating materials can slow the space charge accumulation in the cable insulation, allowing cross-linked polyethylene cables to be used for DC high voltage power supply. The equivalent capacitance of XLPE insulated DC submarine cable up to 320kV AC cable insulation increases with the cable length. During the energy transfer process, the equivalent capacitor and the power supply are continuously charged and discharged, and the charging current is constant. The maximum value can affect the transmission of normal active loads, so there is a theoretical limit for AC submarine cables. Inflatable cable The inflatable submarine cable is similar in structure to the oil-filled cable. It is also insulated with a pre-impregnated paper strip and filled with nitrogen under pressure. The pressurized gas fills the gap between the paper strips, increasing the breakdown voltage. . Inflatable submarine cable can be used for AC and DC transmission, and is more suitable for longer submarine cable network than oil-filled cable. However, due to the need to use high-pressure operation in deep water, this has increased the difficulty of designing cables and their accessories. The cable is generally limited to depths of less than 300m. Longitudinal water blocking is mainly used Pressurized core; add water-blocking substances between the wires and the cable core shielding area to block the diffusion channel of moisture in the cable core. Longitudinal water blocking adopts water blocking powder filling effect, and the water absorption capacity is several tens or even several thousand times of its own. The water absorption strength is large, and the expansion rate is high. After water absorption, it can rapidly expand to form a gel-like substance, blocking the water seepage channel, terminating moisture and moisture. The further diffusion and extension of the cable minimizes the length of the moisture-proof cable. Submarine optoelectronic composite cable design selection Due to the special circumstances of subsea applications, submarine optoelectronic composite cables of different voltage levels need to have different conductive sections, different mechanical strengths, structural features such as seawater leakage and corrosion, and adapt to intertidal, subtidal, and deep-water zones. Different construction methods are used to meet the special needs of offshore wind power industry. Equipment Gasket ,Stainless Steel Gaskets,Gasket For Various Equipment,Non-Standard Shims Of Various Ningbo Metal Sharing Supply Chain Management Co., Ltd , https://www.sharescm.com