一种电炉变压器中性点横差保护方案研究

分析了共铁心式电炉变压器的结构特点,提出将3个单相变压器中性点解开后重新连接,在主变压器和调压变压器中性点之间接入电流互感器,形成电炉变压器中性点横差保护。当电炉变压器发生内部匝间故障、同相不同支路间故障以及相间故障时,中性点横差保护能够可靠动作,同时可作为补偿电容器纵差保护的后备保护。并利用动模试验验证了中性点横差保护的动作性能。试验结果表明:作为电炉变压器纵差保护的有效补充,中性点横差保护可显著提高电炉变压器差动保护的灵敏性和可靠性。

Study on neutral point transverse differential protection scheme for a kind of electric furnace transformer

Analyzes the structure characteristic of common iron core electric furnace transformer,puts forward that reconnected neutral point of three single phase transformers after which were untied,current transformer were connected between the neutral point of the main transformer and voltage-reg?ulating transformer, forms neutral point transverse differential protection of electric furnace transform?er. When interturn fault, same phase but different branches fault and phase fault happened in electricfurnace transformer, neutral point transverse differential protection can reliably act and to be the back?up protection of longitudinal differential protection for compensating capacitor. Using dynamic modeltest verified the action performance of neutral point transverse differential protection. The test resultshows that as the effective supplement of longitudinal differential protection for electric furnace trans?former, neutral point transverse differential protection can markedly improve the sensitivity and reli?ability of differential protection for electric furnace transformer.