Load-flow conditions for HVDC transmission in synchronous networks

The basic purpose for HVDC thigh-voltage direct current) transmission is to transmit a determined value of electrical power from one electrical node to another If there is an AC system in pal allel to an HVDC transmission, the load flow via this parallel AC system can be controlled directly. Since HVDC systems offer possibilities to perform fast load-flow control, they can also be used for improving stability. In this paper load flow calculations of a simplified network are presented. First a comparison between HVDC transmission operating in asynchronous resp. synchronous networks is shown. Synchronous network means that the HVDC transmission works in parallel to an AC system at the same voltage level. It is shown how voltage at the point of installation and how the load angle are influenced due to the synchronous operation. A special regard is drawn to the losses of the transmission. Conditions for minimum total losses are presented. Informer calculations loads are involved. It is shown how they influence the minimum total losses.