| 引用本文: | 罗美玲,国兴超,于晓军,等.基于波形相关性分析的换流变压器零序差动保护方案[J].电力系统保护与控制,2020,48(12):80-89.[点击复制] |
| LUO Meiling,GUO Xingchao,YU Xiaojun,et al.Zero-sequence differential protection scheme for a converter transformer based on waveform correlation analysis[J].Power System Protection and Control,2020,48(12):80-89[点击复制] |
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| 摘要: |
| 通过对换流变压器外部故障切除产生恢复性涌流的分析，得出换流变铁芯可能在涌流的作用下发生饱和，导致灵敏度较高的中性线TA 发生偏置现象，使其测量失真导致零序差动保护误动。为此，提出一种基于波形相关性的换流变零序差动保护新方案。通过分析换流变压器区内故障、区外故障及外部故障切除时零序电流的特点，利用零序差动保护两侧自产零序电流和中性线上零序电流的波形相关性进行识别。通过合理选择电流互感器的极性，使得区外故障时，零差保护两侧的零序电流呈现“穿越性”特征，其波形相似度较高，相关系数为正值。区内故障时，两侧零序电流波形相似度较小，相关系数落入负值区。通过PSCAD/EMTDC大量仿真验证，该判据可准确识别区内与区外故障，不受恢复性涌流的影响，且具有一定的抗TA饱和的能力。 |
| 关键词: 换流变压器 零序差动保护 相关性分析 TA饱和 |
| DOI：10.19783/j.cnki.pspc.190901 |
| 投稿时间：2019-07-26修订日期：2019-11-03 |
| 基金项目:国家重点研发计划智能电网技术与装备重点专项资助(2016YFB0900600);国家电网公司科技项目资助(SGNX0000DKJS1900460)“超/特高压换流变故障性涌流及其对差动保护的影响研究” |
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| Zero-sequence differential protection scheme for a converter transformer based on waveform correlation analysis |
| LUO Meiling,GUO Xingchao,YU Xiaojun,WU Jianyun,HE Jianan,SHOU Haining,ZHENG Tao,LI Lei |
| (State Grid Ningxia Electric Power Limited Company, Yinchuan 750001, China;State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University, Beijing 102206, China;State Grid Ningxia Electric Power Co., Ltd.Electric Power Research Institute, Yinchuan 750001, China) |
| Abstract: |
| Through the analysis of the recovery surge current generated by external fault reversal of the converter transformer, it is pointed out that the commutating iron core may be saturated under the action of the inrush current, resulting in the biasing of the sensitive neutral line TA and causing its measurement distortion to lead to zero. In this paper, a new scheme of commutation-changing zero-sequence differential protection based on waveform correlation is proposed. By analyzing the characteristics of faults in the converter transformer, out-of-zone faults and zero-sequence currents during external fault removal, the zero-sequence differential protection is used to identify the waveform correlation between the zero-sequence currents on both sides and the zero-sequence current on the neutral line. By reasonably selecting the polarity of the current transformer, the zero-sequence current on both sides of the homodyne protection exhibits a "traversal" characteristic when the fault is outside the zone, and the waveform similarity is high, and the correlation coefficient is positive. When the fault occurs in the area, the similarity of the zero-sequence current waveforms on both sides is small, and the correlation coefficient falls into the negative value area. Through a large number of simulations verified by PSCAD/EMTDC, this criterion can accurately identify faults in and out of the zone, is not affected by the recovery inrush, and has some ability to resist TA saturation. This work is supported by the Key Project of Smart Grid Technologies and Equipment of National Key Research and Development Program of China (No. 2016YFB0900600) and Science and Technology Project of State Grid Corporation of China (No. SGNX0000DKJ S1900460). |
| Key words: converter transformer zero sequence differential protection correlation analysis TA saturation |
