Mathematical simulation of thermal state of digital current and voltage transformer in unfavourable weather conditions

Reliable functioning of electric power grids to a large extent depends on the serviceability of each unit in the given power system, subject to the impact of various unfavorable factors, namely grid operation mode and weather conditions, such as elevated ambient temperatures, insolation and no-wind. These environmental parameters have a significant negative impact on the process of heat removal from electrical equipment, which may result in its overheating and breakdown. ISPEU staff have developed and put into operation innovative design digital current and voltage instrument transformers. The purpose of the present study is to examine the impact of insolation, ambient temperature and emergency operating modes on the thermal state of transformers. A mathematical model of heat exchange for a 6(10) kV transformer was developed and verified with the results of physical experiments conducted in an environmental chamber. Heat exchange between the transformer and its environment was simulated for a July day in Sochi in nominal and emergency operating modes, and also with various values of heat conductivity of electrical insulation sealant used. It was discovered that maximum influence on transformer thermal state is exerted by self-heating of instrument resistors at elevated voltage levels.

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Development of a thermal self-diagnostics system for a digital current and voltage instrument transformer

Parfenov

Gotovkina

Lebedev

et al. 2019

IOP Conf. Ser.: Mater. Sci. Eng.

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Ivanovo State Power Engineering University (ISPEU) staff have developed and put into operation innovative designs of digital current and voltage instrument transformers (DCVT) based on resistor dividers performing technical and commercial electric power accounting, and also participating in work of relay protection and automation systems. Thermal self-diagnostics systems working in real time for instrument transformers do not exist in electric power engineering, while thermal examination is often conducted according to maintenance schedules, which negatively impacts the reliability of electrical equipment functioning. Development and building of new systems of self diagnostics for instrument transformer thermal state, revealing temperatures at several points, including values for the most heated up part, in real time, is therefore a vital task, especially for controlling operation of “smart” grids. Based on the results of physical and mathematical simulation of the process of heat exchange between a transformer and its environment at different values of ambient temperature, insolation and grid voltage, methods have been developed to determine the impact of the above factors on the thermal mode of DCVT operation. Algorithm has also been developed for thermal self-diagnostics and thermal protection against overheating of instrument transformers. System of thermal self diagnostics has been developed for 6-220 kV.

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Mathematical simulation of thermal state of digital current and voltage transformer in unfavourable weather conditions

Cited by 3 publications

References 6 publications

Studying the Impact of Weather Conditions and Operating Modes on the Thermal State of the Primary Voltage Converter of a 110 kV Digital Transformer

Studying the Impact of Weather Conditions and Operating Modes on the Thermal State of the Primary Voltage Converter of a 110 kV Digital Transformer

Simulation of heat exchange between a digital instrument transformer and its environment for operation in emergency and unfavorable weather conditions

Development of a thermal self-diagnostics system for a digital current and voltage instrument transformer

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