Abstract：The enormous ground return current caused by HVDC system’s mono-pole ground return operation mode will result in transformers nearby DC biasing . This paper provides a new circuit topology of a neutral blocking DC capacitor controllable opening and broken bridge for suppressing DC biasing. Compared with the traditional blocking capacitor circuit, the increasing ratio of the fault current just after the occurrence of a fault is limited by a DC limiting reactor, which is instantaneous automatic input without control system response. As a result, it avoids the transient current shock to damage the capacitor. This method ensures neutral point effective grounding. Meanwhile, the control system has adequate response time to switch working modes. The structure of the equivalent circuit, and the analytical results of the voltage and current and are given in detail. In addition, the selected bases for parameters of capacitor are also provided. Using PSCAD/EMTDC software, it comparative analyses that the effect of suppressing transient impulse current with or without adding blocking DC device under fault conditions. A blocking device prototype with low-power is established and experimentally investigated. Results prove its validity and practicability.
王振浩, 佟昕, 齐伟夫. 电容隔直可控开断桥法抑制变压器直流偏磁[J]. 电工技术学报, 2013, 28(10): 120-126.
Wang Zhenhao, Tong Xin, Qi Weifu. Blocking DC Capacitor Controllable Opening and Broken Bridge Suppression in Transformer DC Magnetic Bias. Transactions of China Electrotechnical Society, 2013, 28(10): 120-126.
[1] 李鸿志, 崔翔, 刘东升, 等. 直流偏磁对三相电力变压器的影响[J]. 电工技术学报, 2010, 25(5): 88-96. Li Zhihong, Cui Xiang, Liu Dongsheng, et al. Influence on three-phase power transformer by DC bias excitation[J]. Transactions of China Electrotechnical Society, 2010, 25(5): 88-96. [2] 罗建武, 罗文杰. 偏磁的引起和消除方法[J]. 电工技术学报, 1999, 14(6): 73-77. Luo Jianwu, Luo Wenjie. The cause and eliminating method of magnetic-shift[J]. Transactions of China Electrotechnical Society, 1999, 14(6): 73-77. [3] Molinski T S, Feero W E, Damsky B L. Shielding grids from solar storms[J]. IEEE Spectrum, 2000, 37(11): 55-60. [4] 钟连宏, 张尧, 管霖, 等. 直流接地极电流对中性点直接接地变压器影响[J]. 高电压技术, 2003, 29(8): 12-13. Zhong Lianhong, Zhang Rao, , Guan Lin, et al. The influence of current of DC earthing electrode on directly grounded transformer[J]. High Voltage Engineering, 2003, 29(8): 12-13. [5] 何俊佳, 叶会生, 林福昌, 等. 土壤结构对流入变压器中性点直流电流的影响[J]. 中国电机工程学报, 2007, 27(36): 14-18. He Junjia, Ye Huisheng, Lin Fuchang, et al. Influence of soil structure on direct current flowing into neutral point of power transformer[J]. Proceedings of the CSEE, 2007, 27(36): 14-18. [6] 朱林, 韦晨, 余洋. 单相变压器的直流偏磁励磁电流问题及其对保护的影响分析[J]. 电力系统保护与控制, 2010, 38(24) : 158-162. Zhu Lin, Wei Chen, Yu Yang. Analysis of DC bias exciting current of the single-phase transformer and its effect on protection[J]. Power System Protection and Control, 2010, 38(24): 158-162. [7] 赵杰, 黎小琳, 吕金壮, 等. 抑制变压器直流偏磁的串接电阻措施[J]. 电力系统自动化, 2006, 30(12): 88-91. Zhao Jie, Li Xiaolin, Lü Jinzhuang, et al. Study on resistor to restrain power transformer DC biasing[J]. Automation of Electric Power System, 2006, 30(12): 88-91. [8] 郭满生, 梅桂华, 刘东升, 等. 直流偏磁条件下电力变压器铁心B-H曲线及非对称励磁电流[J]. 电工技术学报, 2009, 24(5): 46-59. Guo Mansheng, Mei Guihua, Liu Dongsheng. B-H curve based on core and asymmetric magnetizing current in DC-biased transformers[J]. Transactions of China Electrotechnecal Society, 2009, 24(5): 46-59. [9] 李贞, 李庆民, 李长云, 等. 直流偏磁条件下变压器的谐波畸变特征[J]. 电力系统保护与控制, 2010, 38(24): 52-55. Li Zhen, Li Qingmin, Li Changyun, et al. Harmonic distortion feature of AC transformers caused by DC bias[J]. Power System Protection and Control, 2010, 38(24): 52-55. [10] 梅桂华, 梁文进, 刘艳村, 等. 变压器直流偏磁电流阻容抑制装置的开发应用[J]. 高电压技术, 2009, 35(10): 2581-2585. Mei Guihua, Liang Jinwen, Liu Yancun, et, al. Development of the DC current blocking device in capacitor-resistor for transformer[J]. High Voltage Engineering, 2009, 35(10): 2581-2585 [11] Leonard Bolduc, Michel Granger, Gregoire Pare, et al. Development of a DC current-blocking device for transformer neutrals[J]. IEEE Transactions on Power Delivery, 2005, 20(1): 163-168. [12] 蒋伟, 黄震, 胡灿. 变压器接小电阻抑制直流偏磁的网络优化配置[J]. 中国电机工程学报, 2009, 29(16): 89-94. Jiang Wei, Huang Zhen, Hu Can, et al. Optimized network configuration of small resistances to limit DC bias current of transformer[J]. Proceedings of the CSEE, 2009, 29(16): 89-94. [13] 朱艺颖, 蒋卫平, 曾昭华, 等. 抑制变压器中性点直流电流的措施研究[J]. 中国电机工程学报, 2005, 25(13): 1-7. Zhu Yiying, Jiang Weiping, Zeng Zhaohua, et al. Studying on measures of restraining DC current through transformer neutrals[J]. Proceedings of the CSEE, 2005, 25(13): 1-7. [14] 苑舜, 王天施. 电力变压器直流偏磁研究综述[J]. 高压电器, 2010, 46(3): 83-87. Yuan Shun, Wang Tianshi. Summary of the research on transformer DC magnetic bias[J]. High Voltage Apparatus, 2010, 46(3): 83-87. [15] 张雪松, 黄莉. 基于PSCAD/EMTDC的变压器直流偏磁仿真研究[J]. 电力系统保护与控制, 2012, 40(19): 78-84. Zhang Xuesong, Huang Li. Simulation analysis of DC magnetic bias induced current of transformer based on PSCAD/EMTDC[J]. Power System Protection and Control, 2012, 40(19): 78-84. [16] 张金平, 张辉, 熊敏, 等. 基于串联电容法的变压器中 性点直流电流抑制装置[J]. 电网技术, 2009, 33(20): 147-151. Zhang Jinping, Zhang Hui, Xiong Min, et al.Application of a Series capacitor based transformer neutral DC current blocking device[J]. Power System Technology, 2009, 33(20): 147-151. [17] 李占元, 赵伟, 丁健, 等. 国华台山发电厂主变直流偏磁问题分析与治理[J]. 电网技术, 2009, 33(6): 33-38. Li Zhanyuan, Zhao Wei, Ding Jian, et al. Analysis and reformation on DC bias in main transformer of Guohua Taishan power plant[J]. Power System Technology, 2009, 33(6): 33-38.
2013, Vol. 28 
