Analysis Of Operating Characteristics Of Transformer Under DC Bias

The equipment failure of DC transmission system, the conventional preventive maintenance,monopole operation and debugging of early construction of convertor station, all of these situationwill cause DC transmission system operate at the monopole ground circuit operation mode orbipolar unbalanced operation. At this moment, DC transmission system will cause differentpotential on both sides of the nearby transformers. Then the situation will cause DC bias oftransformer which emerge the dc current flow through the neutral point of transformer. DC bias cannot only make the transformer noumenon cause magnetic saturation, loss increase, localoverheating, aggravate vibration and noise of core, but also will influent the network system towhich the transformer place seriously.This paper mainly content: analyze the influence of transformer magnetic field, excitationcurrent, harmonic component when dc current flow through the neutral point of transformerthrough large electromagnetic simulation software Magnet. And study the vibration whichtransformer produce under different dc current. Then use acoustic simulation software Virtual.Labto analyze the change of sound field of transformer under DC bias. At last, discuss theinfluence of ohmic loss of transformer structure under DC bias through Problem21mode.Then use the same method to observe the core loss and ohmic loss of transformer on apractical transformer mode.This paper analyze the DC bias phenomenon in many ways like magnetic field,vibration and noise, loss and so on, then can research the influences of transformer underDC bias, also provide reliable basis for methods which resistant to DC bias in the future.