An HVDC transmission does not contribute to the short circuit current of the interconnected AC system.
When a high power AC transmission is constructed from a power plant to a major load center, the short circuit current level will increase in the receiving system. High short circuit currents is becoming an increasingly difficult problem of many large cities. They may result in a need to replace existing circuit breakers and other equipment if their rating is too low.
If, however, new generating plants are connected to the load center via a DC link , the situation will be quite different. The reason is that an HVDC transmission does not contribute to the short circuit current of the interconnected AC system.