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

Ying Xue, Xiao-Ping Zhang

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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.
Original languageEnglish
Article numberTPWRS-01743-2015
Pages (from-to)753
Number of pages764
JournalIEEE Transactions on Power Systems
Issue number1
Early online date5 May 2016
Publication statusPublished - Jan 2017


  • AC voltage control
  • HVDC transmission
  • HVDC with controllable capacitor
  • Reactive power control


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  • Elimination of Commutation Failure by Hybrid HVDC System

    Zhang, X-P. & Xue, Y., 10 Nov 2016, IPC No. H02M7/757, H02M7/525, H02M7/515, H02M7/521, Patent No. WO2016/177991, Priority date 5 May 2015, Priority No. PCT/GB2016/051008

    Research output: Patent

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