新型双K值差动保护研究

Novel Differential Protection With Double Restraint Coefficient

突破传统的在差动电流-制动电流平面中分析差动保护特性的方法,从两侧电流相对幅相关系着手,对目前电流差动常用判据的动作特性展开了对比研究,提出差动保护判据的通用数学表达式。在复平面探讨TA饱和对差动电流和制动电流的影响,并利用差动判据的通用数学表达式构造出一种理想的非线性制动判据。该判据从外部故障差动不平衡电流产生的机理出发,根据两侧电流的幅相关系自动调整制动系数,为差动非线性制动的工程应用和推广提供新思路。

To method, which overcome the shortcoming of the common analyzes the differential protection characteristic in the differential currents vs. resistant currents plane, a novel method is proposed according to the relative relationships about the amplitude and the phase between the two side currents. After contrastive investigation of some customarily differential protection schemes, the universal mathematics expression about differential protections is drawn out. Then some discussions on the impact about the TA saturation on the differential and resistant current are given out. According to the universal expression, a perfect non-linear resistant criterion with double resistant coefficient is presented. Due to the mechanism of the differential imbalance current in external faults, this new criterion auto-regulates the resistant coefficient by the amplitude-phase relationship between the two side currents. This novel criterion provides a novel means of how to get a good and spread use of the non-linear resistant differential protection in field.