Research on Operation and Maintenance Strategy of Bias Magnetic Control Device in Zhalute Converter Station

Abstract

The commissioning of Zhalute-Qingzhou (±800 kV UHVDC) project and the measurement of DC bias control of transformers in Zhalute converter station show that it is difficult to choose the treatment scheme because of the large number and variety of transformers in the converter station, including converter transformers, phase modulator boost transformers and station transformers. Finally, 8 resistive devices were selected to complete the bias current treatment of the Zhalute-Qingzhou UHVDC project delivery network. However, due to the different magnitudes of DC bias currents of various transformers in the converter station, and the failure of any one of the control devices and the direct neutralization of the neutral point of the transformer, the bias current of the transformer will exceed the standard, and there is a hidden danger of the DC bias of the transformer at the converter station. In this paper, the influence of one and two faults on the safety of the faulty branch transformer is calculated, and the operation and maintenance strategy is proposed. It provides a certain technical basis for practical engineering problems and has important reference significance for the operation and maintenance of DC biasing devices