A novel adaptive phase selector based on fault component

A novel superimposed phase selector aiming at improving the performance of phase selector in the event of a wide range change of power system operation mode is presented. In this new scheme, the fault component of phase-phase voltage difference is polarized with the fault component of the third phase current. With this arrangement, this element not only adapts to various operating modes of power systems, but is superior to the traditional superimposed phase selectors. For instance, the superimposed phase-phase current difference based phase selector or the superimposed phase-phase voltage difference based phase selector, in terms of selectivity and sensitivity. The advantages of this phase selector can be highlighted especially in the case of the positive-sequence impedance not being equal to the negative-sequence impedance. In addition, this phase selector can reliably identify the single phase-earth fault and the phase-to-phase fault. The results of electro-magnetic transient in DC system (EMTDC) simulation show that the outstanding phase selection performance can be achieved even when the negative-sequence system impedance is extremely unequal to the positive-sequence system impedance. Besides, this phase selector has higher reliability compared to the traditional superimposed based schemes.