Axial and Radial Temperature Distribution of the Valve Side Bushing in UHVDC Converter Transformer Under High Ambient Temperature and Large Current

For the purpose of evaluating the thermal behavior of resin-impregnated paper valve side bushing in UHVDC converter transformer under high temperature and heavy load current environment accurately, operating temperature of converter transformers in±800kV UHVDC JINHUA converter station was measured during the period of height power load in summer, moreover harmonic current spectrum of converter transformer in the side of double 12 pulse converter valve was simulated. Based on these results, a bushing hot-spot temperature measurement imitating 90° celsius oil temperature in converter transformer and 50° celsius air temperature in valve hall was designed. Meanwhile temperature distribution characteristic in the core of resin-impregnated paper valve side bushing was obtained by using axial and radial thermometric method. An exponential function mode is defined for transient hot-spot temperature calculation, and a correction method for IEC steady temperature was proposed. All research results are beneficial for electro-thermal optimization design, thermal test and performance evaluation under operation condition.