摘要：The paper presents the problem of interaction between an LCC HVDC system and a VSC HVDC system.It was shown that the separate operation of an LCC HVDC system under low short circuit power conditions is possible and that at this level of short circuit power it is possible to transfer the same active power through the VSC HVDC system operating in parallel,under the condition that the inverter of this connection operates in AC voltage regulation mode.On the other hand, in certain circumstances it is this mode that may cause the LCC system operating conditions to worsen,which indicates the need for a careful analysis of such cases in order to properly adjust the settings of the relevant control systems.It has been shown that the settings of the voltage regulation system and the PLL system under normal short circuit power conditions can improve the process of the LCC HVDC system returning to operation post-disturbance,while in the condi- tions of reduced short circuit power they make this process more difficult.
