Abstract
The article demonstrates that the operation of transformer equipment beyond the standard service life has become a global trend, although without taking special measures, it is associated with increased failure risks. The high wear degree of transformers creates a potential danger for both consumers and service personnel. The importance of condition and resource assessment continuous monitoring of high-voltage transformers located at energy facilities and industrial enterprises is emphasized. The main reason is the significant wear and tear of transformers in operation and the relatively low renewal rate. At the same time, the online monitoring system implementation takes place very slowly. Therefore, it is necessary to improve the known methods based on the assessment of the load and external temperature influence on the transformer technical condition. One of the commonly used methods is to monitor the hot spot temperature, which is a factor determining the insulation aging. The main positions of the heating control methodology based on load parameters taking into account the ambient temperature are formulated. The development of a computer model based on the dependencies of the IEC 354 load guideline for oil transformers is justified. The dependencies determining the aging acceleration and the equivalent reduction in service life at a given temperature cycle over a controlled time period are given. A model has been developed for calculating the dynamic thermal load, which provides oil temperature calculation in the upper part of the tank and the hot spot temperature calculation. An example of hot spot temperature calculation and reducing the service life of a transformer in operation at Magnitogorsk Iron and Steel Works is considered. The remaining operating life calculations and the influence of the ambient temperature for typical days in winter and summer months were performed. The conclusions about the significant influence of the load schedule and external temperature on the hot spot temperature are confirmed. The developed method is recommended for monitoring the thermal state of furnace transformers operating with abruptly variable loads.
Keywords
power transformer, technical state, operating life, hot spot temperature, mathematical model, computer program, application, recommendations
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