电炉变压器成套保护装置研制

Development of Micropressor-based Assembly Protection Equipment for Furnace Transformer

为弥补当前国内外大容量电炉变压器只有过流保护而无纵差保护的缺失,文中论述了建立电炉变压器纵差保护的关键内容:提出了电炉变压器纵差保护的最佳转角方程,它与传统电力变压器纵差保护的转角方程不同;分析电炉变压器断路器合闸过程中保护的特殊问题并提出对策;电炉变压器两侧纵差的斜率定值很小,以及三侧纵差保护的制动电流计算都与传统电力变压器纵差保护不同;分析电炉变压器低压侧的特殊接线及接地故障时纵差电流特征;电炉变压器后备保护的低压启动具有特征。所研制的保护装置已投产运行。

Currently,there is only over-current protection for large capacity furnace transformer and without longitudinal differential protection（LDP） at home and abroad,in order to remedy the lack development of it,a LDP of furnace transformer is discussed.An optimal compensation equation for LDP of furnace transformer is put forward,which is different from that of traditional transformer.The particular protection problem during the breaker closing of furnace transformer is analyzed and its solution is also presented.As the gradient setting values for longitude difference in two sides of furnace transformer are small,the restraint current calculation of LDP in three sides of furnace transformer is also different from that of traditional LDP of transformer.The characteristic of the current for LDP is analyzed when the low voltage side of furnace transformer has particular wiring and grounding fault.The characteristic for low voltage start of backup protection of furnace transformer is also analyzed.The protection device developed has been put into production.