Application of aluminum alloy cables in offshore wind farms
Release time: 2024-11-13
Application of aluminum alloy cables in offshore wind farms In recent years, wind power generation has developed rapidly, and the total installed capacity of wind power and the annual newly added installed capacity are among the best in the world. However, due to the harsh environmental conditions of wind farms, the cable terminals and cable bodies of the collector lines in the field are prone to damage. Therefore, it is necessary to continuously adopt new materials and processes with advanced technology and reliable performance to improve the operation quality of the collector lines, which is very necessary for the safe and stable operation of wind farms. Power cables are an important part of the collector circuit of wind farms. Usually, the conductors of wind farm cables are aluminum core and copper core. Aluminum core cables and copper core cables each have their own disadvantages. The disadvantages of aluminum core cables are poor flexibility and easy breakage after repeated bending; poor stability and easy corrosion and oxidation; high resistivity, greater energy consumption and loss than copper cores of the same cross-section; poor ductility and inconvenient installation. The disadvantages of copper core cables are high price; heavy weight; high construction and transportation costs. Analysis of the characteristics of aluminum alloy cables The main components of aluminum alloy cable conductors are copper, silicon, magnesium, zinc, manganese, nickel, iron, titanium, chromium, lithium, rare earth, etc. The role of copper is to increase the resistance stability of the conductor at high temperature; the role of iron is to increase the thermal conductivity of the conductor; the role of magnesium is to improve the tensile strength of the conductor; the role of rare earth is to improve the corrosion resistance of the conductor. 1. Electrical properties of aluminum alloy cables Cable compression characteristics: After the aluminum alloy is twisted with special-shaped single wires, the compression coefficient can reach more than 93%. 2. Mechanical properties of aluminum alloy cables The elongation of hard pure aluminum is very low, and it is easy to be damaged or broken during repeated bending. The elongation of soft pure aluminum is much higher than that of hard pure aluminum, but its yield strength is only half of that of copper, and its creep resistance is poor. After a period of installation, the connection is easy to loosen, causing the contact resistance to increase, which brings hidden dangers to safe operation. The mechanical properties of aluminum alloy conductors have the following advantages: High elongation. The elongation of aluminum alloy conductors after annealing can reach 30%, which is close to copper and much higher than aluminum. This also shows that aluminum alloy conductors can withstand greater external forces than aluminum conductors. High strength, good flexibility, and easy to bend. During installation, the bending radius of aluminum alloy conductors is smaller than that of aluminum conductors, and the terminal connection is more convenient. Good creep resistance. The alloying elements in aluminum alloys are treated with special processes, and the creep resistance and compaction properties are greatly improved. When the conductor encounters extreme conditions such as cold flow, overload, and overheating, the connection can also be guaranteed to be stable. 3. Corrosion resistance of aluminum alloy cables The rare earth metals added to aluminum alloy conductors further improve the corrosion resistance of metal materials with aluminum as conductors in terms of chemical properties, and reduce the potential difference between different metals. The smaller the potential difference, the lighter the corrosion. The rare earth elements in the alloy material can fill surface defects, refine the grains, and eliminate local corrosion of the conductor. At the same time, it also brings about the negative shift of the electrode potential of aluminum, acting as an anode, thereby greatly improving the corrosion resistance. 4. Economic performance of aluminum alloy cables Compared with copper core cables, the price advantage of aluminum alloy cables is also obvious. The price of aluminum alloy cables with the same current carrying capacity is only 60%-70% of that of copper core cables. In addition, due to its light weight, it also indirectly reduces the installation cost. Selection of 35kV cable conductors for wind farms For 35kV high-voltage cables used in wind farms, in order to save engineering costs, it is best to use aluminum core conductors. Under the premise of meeting the voltage drop and correcting the current carrying capacity, the appropriate cable cross-section is calculated using economic current density. With the increase in the number of wind farms and the passage of operating time, the shortcomings of aluminum core cables have gradually emerged, mainly reflected in:
