Vekselstrømsoverføring

Vekselstrømsoverføring, often abbreviated as AC transmission, refers to the method of transmitting electrical power using alternating current (AC). This is the predominant method for transmitting electricity over long distances from power generation plants to consumers. AC is generated by rotating electrical machines in power plants and is then stepped up to very high voltages using transformers for efficient transmission. This high voltage reduces the current flowing through the transmission lines, thereby minimizing energy losses due to the resistance of the wires (I^2R losses).

The key advantage of AC for transmission lies in the ease with which voltage can be transformed. Transformers, which are relatively simple and efficient devices, can easily increase or decrease AC voltage. This allows for the voltage to be stepped up for efficient long-distance transmission and then stepped down incrementally at substations closer to the point of use, making it safe and practical for distribution to homes and businesses.

While AC transmission is highly effective, it does have limitations, particularly over extremely long distances. For such applications, high-voltage direct current (HVDC) transmission can be more efficient, as it avoids certain losses associated with AC, such as reactive power losses and skin effect. However, the simplicity and widespread infrastructure for AC systems, along with the flexibility offered by transformers, make AC transmission the standard for most power grids worldwide. The frequency of the AC power, typically 50 Hz or 60 Hz depending on the region, is also standardized within a grid.