Aiming at the problem of power coordinated control of hybrid multi-terminal high voltage direct current(HVDC)transmission system

a nonlinear droop control strategy is proposed. This strategy takes into account the current margin of every converter station. The stability of the DC voltage is maintained by multiple converter stations. The converter stations with more current margin share more power variation

and the stations with less current margin share less power variation. The condition that some converter stations with full load lose response capability to power change is avoided. This control strategy can harmoniously allocate active power for every converter station and effectively reduce the DC voltage static bias. The response speed of the system is improved. The stability analysis of the proposed control strategy is carried out by the root locus method. The simulation results have validated the feasibility and effectiveness of the proposed control strategy.