摘要
在制定云广直流工程换流变压器保护计划时,发现采用基于高压侧相电流之差原理的变压器零序差动保护制动电流算法结果有问题。通过整定计算实例和理论分析,指出该"新算法"用于换流变压器等单侧电源中性点直接接地系统时必然会产生误动;用于高压系统电厂双绕组升压变压器这类双侧电源系统时,所算得的零序制动电流比采用传统算法时的制动电流更小,区外单相接地故障制动效果比传统零序差动保护差。因此,该"新算法"有必要加以改进。
When setting down the converter transformer protection scheme of Yunnan-Guangdong DC project,a poor result is found in the resisting current from a new algorithm based on the principle of phase-current differeatial of transformer’s zero-sequence differential protection at the high volage side.Through example calculation and theoretical analysis,this paper points out that the results of the new algorithm will lead to malfunction as it is used in the single side power source system with neutral-point directly grounding such as converter transformer protection,and also lead to a smaller resisting current than that of the traditional algorithm as it is used in the double side power source system such as double-windings step-up transformer in high voltage power plant,and the zero-sequence resisting current from the new algorithm is smaller than that from the traditional algorithm,resulting in a weaker effect for treating the single phase grounding fault beyond protection zone.Therefore,the new algorithm should be improved further.
出处
《南方电网技术》
2011年第5期77-80,共4页
Southern Power System Technology
关键词
双绕组变压器
零序差动保护
制动电流
double-windings transformer
zero-sequence differential protection
resisting current
