Operating Conditions of Direct-Current Transmission Lines and Back-to-Back Direct-Current Converter Stations Employing Voltage Converters

Abstract

Special features of steady-state and transient operating conditions of direct current transmission (DCT) lines and back-to-back direct-current converter stations (BBS) based on voltage converters (VC) on fully controlled valves (FCV) are considered. An electrodynamic model developed by NIIPT, which includes physical models of BBS and DCT, is used in the study. Converters of the type are shown to be capable of virtually inertialess control of the active power flow, including the possibility of its reversal, of control of reactive power in the inductive and capacitive quadrants, and of operation under conditions of low short-circuit ratios and autonomous demand. The principles of control of BBS on FCV in a voltage conversion system under transient conditions are formulated, one of the aims of which is prevention of current and voltage overloads on the equipment.