The short-circuit current non-periodic components and its application in relay protection and control

Aiming at how to accurately determine the short circuit fault in power system in order to improve the reliability and sensitivity of the relay protection of power system, a method which used short-circuit current in a non-periodic component as a criterion in short-circuit fault was proposed. Using Matlab to extract short-circuit current of the non-periodic component,was then applied the features of the non-periodic component in the short circuit current to the relay protection of power system. The test run results showed that the directional differential protection of non-periodic components was not affected by the influence of line to ground capacitance. Either as a sole major protection, or as a part of the combined protections, it can always accurately identify the short fault of electric system. However, non-periodic components are transient signals with short existence, therefore a signal maintainer is needed during operation.