Space charge could constrain and impact the electric strength of transformer oil-paper insulation. It is also the important factors that lead to oil-paper insulation aging and insulation failure. For converter transformer oil-paper insulation system, understanding the effect of space charge on the electric field distribution distortion of the insulation system is particularly important. Consequently, we analyzed the space charge dynamic characteristic of the multilayer structure of oil-paper insulation mixed system by using the improved electro acoustic pulse system (PEA). The electric field distribution of the multilayer oil-paper insulation system is simulated by using the COMSOL software. Moreover, the electric field distribution of the multilayer oil-paper insulation system before and after addition space charge was comparatively studied in detail. The results show that the polarity of the accumulation charge at the interface between oil gap and oil impregnated insulation pressboard is opposite with the other side of the oil immersed pressboard. Space charge accumulation behavior of the more complex insulation structure can be deduced according to the space charge accumulation model of 2~4 multilayer structure. The electric field distribution is obvious considering the space charge accumulation effect and the traditional Maxwell-Wagner theory. The space charge makes obvious electric field distribution distortion of the mixed oil paper insulation. The results of this study have laid a theoretical foundation for optimizing the electric field distribution of the insulation system or inhibiting the space charge accumulation.
KEY WORDS :oil-paper insulation;pulsed electro-acoustic (PEA);space charge;accumulation model;electric field distribution;
图6
“油浸纸板+油隙+油浸纸板”3层结构油纸绝缘混合体系的空间电荷积聚特性
Fig.6
Space charge accumulation behavior of the “oil immersed pressboard+oil gap+oil immersed pressboard”
图7
空间电荷在“油隙+油浸纸板+油隙+油浸纸板”4层结构油纸绝缘混合体系的积聚模型
Fig.7
Space charge accumulation model of the ‘oil gap + oil immersed pressboard + oil gap + oil immersed pressboard’
图8
实测“油隙+油浸纸板+油隙+油浸纸板”4层结构油纸绝缘混合体系的空间电荷特性
Fig.8
Space charge accumulation behavior of the “oil gap + oil immersed pressboard + oil gap + oil immersed pressboard”
图9
在12 kV/mm下4层新油纸稳态电场强度分布
Fig.9
Electric field distribution of the four layers of oil-paper insulation
图12
“油隙+油浸纸板+油隙+油浸纸板”4层结构油纸绝缘混合体系的分层示意图
Fig.12
Configuration of the space charge added into the ‘oil gap + oil immersed pressboard + oil gap + oil immersed pressboard’
图13
加入的空间电荷在“油隙+油浸纸板+油隙+油浸纸板”4层结构油纸绝缘混合体系的分布
Fig.13
Distribution of the added space charge in the ‘oil gap + oil immersed pressboard + oil gap + oil immersed pressboard’ system
图14
加入空间电荷后“油隙+油浸纸板+油隙+油浸纸板”4层结构油纸绝缘混合体系的电场分布
Fig.14
Electric field distribution of the ‘oil gap + oil immersed pressboard + oil gap + oil immersed pressboard’
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