Table 1 Characteristics of LCC and VSC-based HVDC systems
From: Circuit breakers in HVDC systems: state-of-the-art review and future trends
Feature | LCC-based technology | VSC-based technology |
|---|---|---|
Basic element | Thyristor-based technology | IGBT-based technology |
Capability | Higher voltage and power capability—good overload capability | Lower voltage and power capability—weaker overload capability |
Power flow reversal | Power reversal by changing voltage polarity | Power reversal by changing direction of current flow |
Active/reactive power | Consumes large amount of reactive power | Independent control of active and reactive power |
Overall cost | Lower station losses—Lower capital cost | Higher station losses—Higher capital cost |
Harmonic related factors | Harmonic filters required—Large site area | Small/no filters required—Compact size area |
AC network limits | Requires stronger AC systems | Possibility to connect to weak AC systems |
Black start | Black start capability needs additional equipment | Black start capability |
Form of storing energy | Store energy inductively | Store energy capacitive |
Commutation issues | Possibility to commutation failures | Avoidance of commutation failure |
Cables | Require use of MI cables | Ideal for use with XLPE cables |
Fault related performance | Ability to withstand DC fault current—vulnerable to AC side faults | More vulnerable to DC side faults |