The Fuzzy Diagnosis Of The Transformer Inrush Current Based On The Multi-criterions

Power transformers are key components in power system, security and stability of transformers are both important and necessary to power system operation.In this thesis, the advantages and disadvantages of several methods for checking inrush current are discussed. According to the characters of the inrush current and the feature of the identification methods, this thesis proposes three new criterions to identify the inrush current, which include fuzzy degree of nearness principle, improved interruptive angle principle and sine principle. This thesis adopts fuzzy theory to make all criterions fuzzy, and selects four criterions to identify the inrush current. At last, they are connected by the fuzzy set theory to identify the inrush current fuzzily.This thesis verifies the scheme by dynamic analog test. The results of dynamic simulation show that the scheme can diminish a lot of defects of transformer protection and improve the performance. It also makes these criterions'dominance complementary and distinguishes internal fault current from inrush current effectively.