Substation is the place where the voltage changes. In order to transmit the power from the power plant to a far place, the voltage must be increased to become high-voltage power, and then reduced as needed near the user. The work of voltage rise and fall depends on our substation. In the above power transmission process, we use our DC transmission technology, because DC transmission has irreplaceable advantages in long-distance, high power, low loss transmission and other aspects.
The function of converter is embodied in this: at the transmission end of the transmission line, the AC of the AC system is sent to the rectifier through the converter transformer in the converter station, and then the high-voltage AC is converted into high-voltage DC and then sent to the DC transmission line. The DC power is sent to the inverter in the receiving converter station through the transmission line, which changes the high-voltage DC power into the high-voltage AC power, and then the power is transmitted to the AC system through the converter equipment.
For example, the mobile phone charger we are using as a “converter station” is plugged into a 220 V AC power outlet, the data line is equivalent to a 5 V “DC line”, and the output power through the charger becomes a 5 V DC power for mobile phones.