Research On Protection Of Power Transformer Based On Fuzzy Multi-Criteria

Power transformer belongs to a class of vital component in electric power system. It plays a role of changing energy and voltage in the whole power system. Its safe operation is directly relative to the stable operation. As the main protection for years, differential protection has a fatal problem:it can not distinguish the magnetizing inrush current and the internal fault current. Taking the transformer of DongPeng substation in HuiZhou, Guangdong as an example, the setting of main and back up protection is illustrated in detail. The paper analyses many theory of the current distinction between transformer inrush current and fault current and their problems and puts forward a method which is using the fuzzy recognition theory. At last, we select five criterions:the second harmonic principle, interruptive angle principle, the principle according to the content of the waveform, transformer terminal voltage and the principle based on the ratio of voltage and fluxional differential current. The method mentioned was verified by the operation of main transformers in working. Unlike the traditional protection of certain deficiencies, the use of fuzzy recognition theory constituting the inrush current program improves the performance of the transformer protection.