核电站辅助变压器缺相保护研究

辅助变压器缺相检测是核电厂中最为关心的问题。一些核电厂的事件表明,变压器轻载时高压侧的缺相可能很难被现有的电气保护方案检测到。如果未能及时发现缺相状态,变压器不能与系统隔离,则可能会导致关键的电机驱动负载跳闸以及电厂安全系统的损失。然而,重负载到中等负载变压器的缺相条件可以通过传统的保护方案可靠地检测和保护。相反,轻负载或空载变压器可靠的缺相检测是具有挑战性的。本文介绍了核电站辅助变压器缺相的问题,提出了适用于大多数电力变压器的线路变压器缺相保护方案。新的方案使用光学电流互感器能够可靠检测重负载到中等负载变压器的缺相也可以可靠检测轻负载或空载的变压器缺相。

Research on Open Phase Protection For Auxiliary Transformer

Open phase Detection is of prime concern in the nuclear industry. Events at several nuclear power plants have shown that the open phases on the HV side of a transformer may be difficult to detect by existing plant instrumentation and electrical protection schemes. If an open phase condition is not quickly detected and the transformer not isolated from the system, tripping of critical motor driven loads and loss of plant safety systems can occur. An open phase condition on heavily loaded to moderately loaded transformers can however be reliably detected and protected against with conventional protection relay schemes. Conversely, reliable open phase detection for all transformer connections which are lightly loaded or unloaded is challenging.This paper describes the issues from loss of a phase for nuclear power plants auxiliary transformers and proposes a new universal protection scheme applicable to most power transformer configurations. The new scheme uses optical CTs to reliably detect open phase from heavy loads to medium load transformers and reliably detect open phase from no load transformer.