AC Transmission Emulation Control Strategy in VSC-HVDC systems: general criteria for optimal tuning of control system

Abstract

AC Transmission Emulation Control Strategy is a promising way to control the ordered active power flow in a VSC-HVDC system as a function of the phase angle over the parallel AC interconnection. The main advantage of this strategy is that no direct operator active power set-point dispatch is needed: HVDC interconnection basically behaves like an alternating current (AC) transmission line characterized by a proper impedance. Despite the high-level control strategy seems relatively simple the choice of an appropriate set of parameters is essential in order to preserve system stability on wide and appropriate grid support in N-1 condition. In light of this need, the paper introduces general criteria to follow for optimal tuning of VSC-HVDC control system in AC Transmission Emulation Control mode. It can be considered as a general methodology that can assist TSO in selecting those parameters of VSC-HVDC control system in AC Transmission Emulation Control mode which mainly affect the HVDCs behaviour in the interconnected power systems.