Principle and algorithm of reactive power management for LCC-based parallel MTDC transmission system

The two-terminal HVDC technology based MTDC (multi-terminal DC transmission) system has already been applied in pratical projects and it has great potential for large capacity and long distance power transmission. Reactive power management design is a necessary part of system design, and it is very important to ensure the stability and security of MTDC transmission system. This paper introduces the technical characteristics of the two-terminal HVDC technology based MTDC system at first. Then the basic principle and algorithm of reactive power management are discussesed in detail, considering different operation modes, restriction conditions and primary data needed. Next, the detailed calculation procedure is described in this paper to calculate the switching order of reactive power compensation equipment. At last, a study case of a four-terminal parallel LCC-MTDC system is analyzed to prove the validity of this algorithm.