Topology type of HVDC | Methods of FRT | Objectives | Performance | Economy | Complexity | Superiority |
---|---|---|---|---|---|---|
LCC-HVDC | Voltage control | •  Capacitor bank •  Rectifier station •  Controlled voltage source | •  Power balance achieved •  Voltage obtained •  System stability enhanced | **** | ** | ** |
DC-link current control | •  PMSG •  Grid-side converters •  Rectifier firing angle | •  Power reduction without communication •  Undesired tripping avoided | **** | **** | **** | |
Frequency control | •  Power flow •  Grid frequency controllers •  Capacitor | •  Frequency obtained •  Power balance achieved •  FRT realized | **** | **** | **** | |
VSC-HVDC | Chopper resistor [147] | •  Converter station •  Wind farm excess energy •  Power of unloading resistance | •  Dynamic reactive support provided •  Power balanced | *** | **** | *** |
Voltage control | •  Controlled voltage drops •  Coordinated control scheme •  Onshore station | •  Fast power reduction achieved •  Communication delay eliminated •  Over-voltage control ability improved System stability increased | **** | *** | *** | |
Frequency control | •  Capacitors •  WTs •  Onshore VSC stations | •  Frequency extremes and rate reduced •  Frequency deviation eliminated •  SFD alleviated •  Frequency support provided | *** | *** | **** | |
WT output control | •  Reactive power compensation •  Receive end converters •  Power reduction factor •  Positive-sequence-voltage-dependent (PSVD) | •  DC voltage limited •  AC grid stability improved •  FRT compliance improved | *** | *** | **** | |
DC protection | •  MMC •  DC circuit breakers •  Hybrid circuit breaker | •  Resiliency of DC faults enhanced •  Continued operation ability improved •  Switching time shortened •  Transient response augmented | *** | *** | **** | |
Hybrid-HVDC | AC fault protection | •  Overvoltage fixed firing angle •  AC and DC components of voltage | •  Inverter-side overvoltage reduced •  Safety and stability maintained | *** | *** | **** |
DC fault protection | •  DC chopper (DCC) •  Voltage-dependent current order limiter (VDCOL) •  Short-term overload capacity of MMC •  HB-MMC •  High rating series diode valve | •  Unbalanced power eliminated •  Commutation failure suppressed •  VSC DC overvoltage suppressed •  Electric eliminated •  DC overvoltage level reduced •  Fault currents blocked | *** | *** | **** | |
DR-HVDC | DC fault protection | •  WT current •  WT converters •  FB-MMC | •  System fast recovery facilitated •  Potential overcurrent risk reduced •  Semiconductor losses decreased | *** | *** | **** |
AC fault protection | •  Communication-free LVRT strategy •  Voltage control •  Current control | •  Voltage restoration enhanced •  Rotor angle stability strengthened •  Rated power delivery resumed | *** | *** | **** |