METHOD FOR MERGING NON-OPERATING STATION INTO OPERATING SYSTEM IN MULTI-TERMINAL FLEXIBLE DIRECT CURRENT TRANSMISSION SYSTEM

摘要

Disclosed is a method for merging a non-operating station into an operating system in a multi-terminal flexible direct current (DC) transmission system. The method comprises the following: selecting STATCOM operation mode at a non-operating station; cutting off a bypass switch on the alternating current (AC) side and connecting a charging resistor to an AC line; closing an AC feed-in switch and, by means of the charging resistor, pre-charging the non-operating-station converter valve; closing the bypass switch upon completion of pre-charging; selecting a constant DC voltage control mode at the non-operating station so as to carry out unlocking; controlling the difference between the non-operating-station DC voltage value and the operating system direct voltage value such that said difference remains within an allowable range; closing a pole-connection device on the DC side of the converter of the non-operating station; and switching the non-operating station from STATCOM operation mode to a DC operation mode, whereupon the non-operating station is merged with the operating system. The method enables an operating station to continue operating and checks DC overcurrent and AC overcurrent produced as a result of a non-operating station connecting to a network, thereby enabling a non-operating station to safely and reliably connect to a network.