The Impact of Current-Transformer Saturation on Transformer Differential Protection
The Impact of Current-Transformer Saturation on Transformer Differential Protection
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DOI：
10.1109/tpwrd.2014.2372794
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发表时间：
2015-06
影响因子：
4.4
通讯作者：
Michael Stanbury;Z. Djekic
中科院分区：
文献类型：
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作者：
Michael Stanbury;Z. Djekic
电流互感器（CT）饱和对差动保护方案的运行有重大影响。Transformer差动保护必须在外部故障CT饱和期间保持安全性，同时保持低幅度内部故障的高灵敏度和操作速度。继电器制造商为保护工程师提供很少的信息或指导，以充分设置继电器来实现这些目标。如果工程师对电流互感器饱和期间的继电器行为缺乏深入的了解，他或她可能会犯下设置实施错误，这可能会导致虚假跳闸或跳闸失败，造成灾难性后果。本文研究了CT饱和对Transformer差动继电器的影响，以提供有关方案行为的指导。有人发现，谐波阻塞触发CT饱和，这是一个显着的效果，这是没有描述的文献或继电器手册。对这种效应进行了建模，并通过CT模拟、继电器二次注入和大电流一次注入验证了模型的准确性。它表明，谐波阻断提供了有效的安全性，防止由CT饱和引起的骚扰跳闸。它还表明，传统的高斜率2的使用大多是多余的谐波阻塞启用。
Current-transformer (CT) saturation has a major impact on the operation of differential protection schemes. Transformer differential protection must maintain security during CT saturation for external faults while preserving high sensitivity and speed of operation for lower magnitude internal faults. Relay manufacturers provide very little information or direction for protection engineers to set relays adequately to achieve these goals. If an engineer lacks a deep understanding of relay behavior during CT saturation, he or she could make setting implementation mistakes that may lead to spurious trips or failures to trip with catastrophic consequences. This work investigated the impact of CT saturation on transformer differential relays in order to provide guidance on scheme behavior. It was discovered that harmonic blocking is triggered by CT saturation-a significant effect which is not described in the literature or relay manuals. This effect was modeled and the model's accuracy was verified with CT simulations, relay secondary injections, and high current primary injections. It is demonstrated that harmonic blocking provides effective security against nuisance trips caused by CT saturation. It is also shown that the traditional use of a high slope 2 is mostly redundant wherever harmonic blocking is enabled.