دانلود Reactive Power and AC Voltage Control of LCC HVDC System with Controllable Capacitors

Abstract

It is well-known that traditional LCC HVDC system is not able to control its reactive power and terminal AC voltages. This paper investigates the reactive power and AC voltage control  at  the  inverter  side  of  the  LCC  HVDC  system with controllable  capacitors.  The system’s ability  of  operating  under negative  extinction  angle  is  utilized  to  achieve  a  wide  range  of reactive power control and, in particular, the ability of exporting reactive  power.  In  connection  with  the  inverter  AC  terminal voltage or reactive power control, among different control possibilities at the rectifier side, active power control is  desirable since large variations of active power transfer is very unfavorable.  Detailed  theoretical  analysis  is  carried  out  first  to show the reactive power controllability, and the capacitor voltage level is selected based on the desired control range. In addition, a new extinction angle measurement approach is proposed for negative  extinction  angle  measurements.  The  effectiveness  of  the reactive power/voltage control capability for the proposed system is  validated  through  simulation  results  using  Real  Time  Digital Simulator  (RTDS).  To  verify  the  effectiveness  of  the  reactive power  and  voltage  control,  CCC  HVDC  and  LCC  HVDC  with SVC  are  also  set  up  in  RTDS,  and  simulation  comparisons  are made. Furthermore, contribution to AC voltage control in power system using the proposed method is demonstrated through simulation  results  on  the  modified  two-area  four-machine  AC power system.