HVDC advantages and disadvantages

HVDC links are being used worldwide at power levels of several gigawatts with the use of thyristor valve. So here this article gives information about the advantages and disadvantages of HVDC to know more details about it. 

Advantages of high voltage DC transmission :

  • Fault clearance in HVDC is faster, therefore the DC transmission system possesses improved transient stability
  • Size of the conductor in DC transmission can be reduced as there is no skin effect
  • Cost is less as compared to the AC transmission
  • HVDC tower is less costly 
  • No requirement of reactive power
  • No system stability problem
  • HVDC require less phase to phase and ground to ground clearance
  • Require less number of conductor for same power transfer
  • Improve line loading capacity
  • To ac system at different frequencies can be interconnected through HVDC transmission lines
  • HVDC is preferred as it requires no charging current 
  • Power loss is reduced  with DC just because of fewer numbers of lines are required for power transmission
  • HVDC is a more flexible system

Disadvantages of high voltage DC transmission :

  • Expenses inverters with limited overload capacity
  • HVDC is less reliable
  • IN HVDC very accurate and lossless power flows through DC link
  • The disadvantages of HVDC are in conversion, switching, control, maintenance
  • Lower availability than the AC system
  • HVDC  is very complicated 
  • The circuit breaker is used in HVDC for circuit breaking, and Inverter and rectifier terminals will generate harmonics which can be reduced by using active filters, which are also very expensive
  • HVDC does not have transformers for changing the voltage levels
  • Heat loss occurs in converters substation