A Novel Sensor to Measure the DC Bias in Distribution Power Transformers

Abstract

With the advantages of long-distance transmission and correlation of the power system, HVDC project has become increasingly popular of implementation in china. When the HVDC system operated in mono-pole ground return mode, the DC bias occurred by the accumulated DC current at the point of common coupling of transformers and cause series bad influences to transformer itself. In order to reduce the DC bias phenomena in the secondary side of the transformer, it is of prime need to accurate and fast sense the DC bias. Firstly, this paper narrative the effect of DC bias to transformers. Then, a novel DC bias sensor is raised, which achieve the objective by measuring the DC voltage that across the resistance caused by the following of DC current. Last, simulations are taken to assess the accuracy and validity of the proposed DC bias sensor, and simulation results prove that the proposed sensor can accurately and quickly sense the DC bias.