A Transformer DC Bias Simulation and Suppression Method Based on Ground Potential Rising

Abstract

The invention discloses a method for simulating and inhibiting direct-current magnetic biases of transformers based on earth potential rise. The method comprises the following steps: calculating earth potentials of earth points of transformers according to distribution of direct-current earth electrode potentials; building an electromagnetic transient model of an alternating-current and direct-current system in simulation software; simulating the influence of earth current of a direct-current transmission project on transformer excitation branches by rising the earth potentials of the earth points of the transformers; analyzing and judging the degree of influence on the alternating-current and direct-current system by detecting harmonic components in alternating-current bus voltage and current and transmission power of the direct-current transmission project, and selecting proper transformer direct-current magnetic bias inhibition measures according to simulation judgment results to inhibit the direct-current magnetic biases of the transformers. According to the method, the actual influence of the direct-current magnetic biases of the plurality of transformers with different types and parameters in the same transformer substation / convertor substation under the same earth potential can be effectively simulated, the direct-current magnetic bias inhibition measures are correctly selected, and the running safety of the transformer substation and a power grid is improved.

Description

technical field [0001] The invention belongs to the field of transformer DC bias, and relates to a method for simulating and suppressing transformer DC bias based on ground potential rise. Background technique [0002] When the single pole ground circuit of the DC transmission project is running, it is relatively easy to cause the DC bias phenomenon of the AC transformer and the converter transformer. refer to figure 1 , when the site of the substation and converter station is close to the grounding pole of the DC transmission system, under the operation mode of the single pole ground loop of the DC transmission system, the large grounding current makes a certain DC current flow through the neutral point of the transformer or the transformer winding , causing DC bias, causing saturation of the transformer core, making it work in the non-linear region of the core saturation curve, such as figure 2 As shown, the excitation current of the transformer is distorted in the half...

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