Analysis Of Factors Affecting Operation Reliability Of Transformers And Countermeasures

The transformer is one of the key equipment in power systems, which bears somefunctions such as voltage conversion, power transmission and distribution, and it is themost critical part in transmission systems. Its health and operating conditions has a directimpact on the safe operation of the whole power system, and its failure not only affects thetransmission capacity, but also may result in large-scale blackouts of power systems, whichbrings about national economy and people’s daily life losses. Therefore, it is a urgent needto improve the transformer operation, maintenance and technical management level and toreduce the risk of transformer failure.Firstly, this paper discusses control requirements of operating temperature oftransformers. The reason analysis is performed through common performancecharacteristics of the transformer temperature anomaly. Also the temperature anomalyreasons and on-site processing are described, analyzed and expounded according to severalexamples of abnormal failures in judging and the processing temperature of the transformer,and the transformer temperature anomaly detection method and preventive measure areproposed.Secondly, common malfunction of differential protections is summarized and analyzed,and operating countermeasures are explored. The ability to identify inrush current bywaveform symmetry principle is analyzed and compared according to the malfunctionaccident of differential protection for a no-load transformer. The "two out of three"blocking mode in differential protection based on waveform symmetry principle isproposed, and operating experience shows that this blocking mode approach is effective.The malfunction reasons of non-electricity protection are analyzed and summarized. Also,the impact of some factors such as the inrush current, DC grounding and secondaryinterference on non-power protection is analyzed, and several measures in terms of systemoperation and secondary anti-interference are proposed. The malfunction reasons ofbackup protection are analyzed, and based on a malfunction case of back-up a solutionscheme is proposed by reasonable arrangement of operating modes and reasonableadjustments of configuration of backup protection. In addition, a preliminary study of microcomputer protection technology is conducted.Finally, some factors to affect overload are analyzed. Specific running load limit iscalculated through changing load and referring to “oil-immersed transformer load guide”,and preventive measures to ensure normal running of transformers is proposed.