Aspects on infeed of multiple HVDC into one ac network

The paper covers the fundamental aspects of integration of multiple HVDC links feeding power into different points in the same ac network area. Considering that the number of power systems that includes this type of application of HVDC is increasing, the performance needs to be studied in detail. There are a number of technical aspects related to multiple infeed configurations with HVDC transmission links. Focus on critical network conditions where the strength of the system is relatively low as compared to the amount of power that the HVDC transmission links are feeding into the system will be given in this paper. In those cases the phenomena of concern that might occur which could result in adverse interaction among the HVDC transmission links and the receiving ac network are discussed. The following basic issues are addressed in the paper: voltage and power stability; coordination of power or voltage modulation between different HVDC links for stabilization of the ac network; need of coordination of recovery control based on dynamic performance during fault and during recovery of the fault; commutation failure interaction between different HVDC converters; frequency stability, overvoltages and harmonic instability due to resonances.