ON-LINE DEBLOCKING AND BLOCKING CONTROL METHOD FOR EXTRA-HIGH VOLTAGE DIRECT CURRENT TRANSMISSION PROJECT CONVERTER

摘要

An on-line deblocking and blocking control method for extra-high voltage direct current transmission project converter; through control of a firing angle of an SCA shielding pole layer,, a self-calculation trigger angle is outputted, allowing the voltage across two ends of a valve group to be zero; at the same time tracking current of the valve group using a PI regulator, pulling open a bypass breaker BPS after the current in the bypass breaker BPS is reduced to a breaking capacity so as to complete an on-line deblocking process of the valve group. In a blocking process, transfer of direct current is completed by limiting the firing angle outputted by a current control amplifier, and then implementing a by-pass pair and blocking, thus achieving blocking of the valve group online. The method has faster deblocking and blocking speed, a smaller transient state (overvoltage, overcurrent) in a start process, has a smaller reactive power impact on an alternating current system, while also ensuring a smoother change process of voltage, current, active power and reactive power in the deblocking and blocking process, and is simpler in control logic.