A neutral DC current blocking device for grounding transformer based on inverse parallel thyristors protection

作者：Wang Sheng^*; Lu Jiming; Mao Chengxiong; Wang Dan; Mei Guihua

来源：Transactions of China Electrotechnical Society, 2010, 25(10): 183-190.

• DC bias
• HVDC
• Neutral DC current blocking devices
• Neutral points
• Transformer

When HVDC power system operates in ground return mode, the AC grounding transformers around the electrodes always suffer from DC biases due to the DC currents through their neutral points. In this paper, a novel transformer neutral DC current blocking device (NCBD) based on inverse parallel thyristors protection is proposed and developed to solve such problem. Based on the analysis of the topology and operating principles of NCBD, the main circuit is simplified by removing the front-end rectifier circuit and the turn-off circuit of thyristor. Thus, the cost of the device can be cut down a lot. Moreover, the reliability and intelligence of NCBD are improved by its dual redundant structure, which is made up of a set of hardware integrated circuit and a set of microcomputer measure-controlling system. Simulation results, high current tests and field operation results confirm that the NCBD can resolve the demand of DC bias restraint effectively, and provide a practical based engineering solution.

• 出版日期2010
• 单位华中科技大学