Question

Describe the techniques used to transmit and distribute HVDC power. Please type answer.

Answer 1

For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses. For underwater power cables, HVDC avoids the heavy currents required to charge and discharge the cable capacitance each cycle. For shorter distances, the higher cost of DC conversion equipment compared to an AC system may still be justified, due to other benefits of direct current links. HVDC uses voltages between 100 kV and 1,500 kV.

One technique attempted for conversion of direct current from a high transmission voltage to lower utilization voltage was to charge series-connected batteries, then reconnect the batteries in parallel to serve distribution loads.While at least two commercial installations were tried around the turn of the 20th century, the technique was not generally useful owing to the limited capacity of batteries, difficulties in switching between series and parallel connections, and the inherent energy inefficiency of a battery charge/discharge cycle.

the grid controlled mercury-arc valve became available for power transmission during the period 1920 to 1940.mercury-vapor valves and a 12 kV DC transmission line, which also served to convert 40 Hz generation to serve 60 Hz loads.

new HVDC systems have used only solid-state devices, in most cases thyristor valves.Development of thyristor valves for HVDC began in the late 1960s.

Line-commutated converters have some limitations in their use for HVDC systems.