基于幅相平面的三区域差动保护方法

在幅相平面上对双端差动保护进行分析,传统的全电流差动保护灵敏性较低且与安全性存在矛盾。为使之兼具灵敏性与安全性,充分利用了不同故障时的两端电流相对幅相关系,提出将整个幅相平面划分为包含制动区、模糊区以及动作区的三区域差动保护方法,并利用短数据窗小矢量算法计算差动电流与制动电流来区分模糊区时为区外故障电流互感器(TA)饱和还是区内高阻故障。当为区内高阻故障时,保护可灵敏动作。该方法不仅解决了传统电流差动保护判据灵敏性与安全性间存在矛盾的问题,同时具有在区外转区内故障时不受TA饱和闭锁时间的影响而快速动作的优点。最后,由仿真验证了所提方案的有效性。

Three-region Differential Protection Method Based on Amplitude-phase Flat

The characteristics of two-terminal differential protection on the amplitude-phase flat are discussed. The sensitivity of traditional current differential protection is low and in contradiction with security. By making full use of the relative amplitude and phase relationship of different faults, a new method of dividing the amplitude-phase flat into three regions including the action region, brake region and fuzzy region is proposed, which is capable of meeting both sensitivity and security requirements of current differential protection. Moreover, the proposed method is used to calculate the differential current and restrained current by using the short data window phaselet algorithm to distinguish the external fault causing current transformer saturation and internal high-impedance fault. If it is internal high-impedance fault, protection can act sensitively. The proposed method can solve the contradiction between sensitivity and security, and is capable of acting rapidly when external fault converts to internal fault while ensuring freedom from the influence of the blocking time of current transformer saturation. Simulative results have proved the effectiveness of the proposed method.