Hadi Zibandeh - Mazandaran Regional Electric Company

Today, many HVDC systems are in operation around the world, and many more are underconstruction and operation. These systems carry a large amount of electrical power over longdistances with overhead transmission lines or via cables and submarines with better economicefficiency and without technical problems. This paper describes the principles of operation ofHVDC systems and their control, which includes the performance of HVDC converters, thereactive power characteristic of HVDC converters, and the effect of AC system power onHVDC system. As the heart of an HVDC system, performance and control of its converters areessential. The HVDC control system is then fully discussed. In the next section, the advantagesand disadvantages of the HVDC system are described. Connecting two different powernetworks, lower power losses and increased controllability are the most important advantagesof the HVDC system. At the end, conclusions and suggestions are given.

Power transmission, HVDC system, inverter, rectifier, controllability